Rear Ho2S Monitor

Rear HO2S Signal 

A functional test of the rear HO2S sensors is done during normal vehicle operation. The peak rich and lean voltages are continuously monitored. Voltages that exceed the calibratable rich and lean thresholds indicate a functional sensor. If the voltages have not exceeded the thresholds after a long period of vehicle operation, the air/fuel ratio may be forced rich or lean in an attempt to get the rear sensor to switch. This situation normally occurs only with a green catalyst (< 500 miles). If the sensor does not exceed the rich and lean peak thresholds, a malfunction is indicated.

2005 MY and beyond vehicles will continuously monitor the rear HO2S signal for high voltage, in excess of 1.1 volts and store a unique DTC (P0138, P0158). An over voltage condition is caused by a HO2S heater or battery power short to the HO2S signal line.

2011 MY and beyond vehicles with Conti-Moto CBP-A2 PCM will also continuously monitor the rear HO2S signal for out of range low voltage, below -0.2 volts and store DTC P2A01, P2A04. An out of range low voltage condition is caused by swapped sensor wires (sensor signal and signal return) and sensor degradation.

Furthermore, the rear HO2S signal will also be monitored continuously for circuit open or shorted to ground beginning 2011 MY vehicles as the PCM hardware becomes capable. An intrusive circuit test is invoked whenever the HO2S voltage falls into a voltage fault band. A pull-up resistor is enabled to alter the HO2S circuit characteristics. A very high HO2S internal resistance, > 1 M ohms, will indicate an open HO2S circuit while a low HO2S internal resistance, < 10 ohms, will indicate a HO2S circuit shorted to ground. Both HO2S circuit open and shorted to ground malfunction will set DTC P0137, P0157 if the fault counter exceeds the threshold.

DTCs Sensor 2	P0136 - HO2S12 No activity or P2270 - HO2S12 Signal Stuck Lean P2271 - HO2S12 Signal Stuck Rich P0156 - HO2S22 No activity or P2272 - HO2S22 Signal Stuck Lean P2273 - HO2S22 Signal Stuck Rich
Monitor execution	once per driving cycle for activity test
Monitor Sequence	> 30 seconds time in lack of movement test (UEGO only), > 30 seconds time in lack of switch test, front HO2S/UEGO response test completed, Stream 2 HO2S circuit open/short to ground test time slice completed.
Sensors OK	ECT, IAT, MAF, MAP, VSS, TP, ETC, FRP, FVR, DPFE EGR, VCT, VMV/EVMV, CVS, CPV, EVAPSV, FTP, CKP, CMP, ignition coils, injectors, no misfire DTCs, no system failures affecting fuel, no EVAP gross leak failure, UEGO/HO2S (front and rear) heaters OK, no "lack of switching" malfunction, no "lack of movement" malfunction (UEGO only), no UEGO/HO2S (front and rear) circuit malfunction, no rear HO2S out of range low malfunction, no UEGO FAOS monitor malfunction, no front HO2S/UEGO response rate malfunction
Monitoring Duration	continuous until monitor completed

Entry Condition	Minimum	Maximum
Stream 1 HO2S not in CSD recovery mode
Flex Fuel Composition not changing
Not in Phase 0 of Evaporative System Monitor
No Purge System reset
Purge intrusive test not running
Not performing CSER spark retard
Engine Coolant Temp	150 °F	240 °F
Intake Air Temp		140 °F
Time since entering closed loop fuel	10 seconds
Inferred Catalyst Midbed Temperature		1600 °F
Heater-on Inferred Sensor(s) 2/3 HO2S Temperature Range	400 °F	1400 °F
Sensor(s) 2/3 HO2S heater-on time	90 seconds
Short Term Fuel Trim Range	-9%	11%
Fuel Level (forced excursion only)	15%
Throttle position	Part throttle
Engine RPM (forced excursion only)	1000 rpm	2000 rpm
UEGO ASIC not in recalibration mode
No air passing through during valve overlap (scavenging).
Battery Voltage	11.0 Volts	18.0 Volts

Does not exceed rich and lean threshold envelope: Rich < 0.42 volts Lean > 0.48 volts

Monitor ID	Test ID	Description	Unit
$02	$01	HO2S12 sensor switch-point voltage	volts
$06	$01	HO2S22 sensor switch-point voltage	volts
$03	$01	HO2S13 sensor switch-point voltage	volts
$07	$01	HO2S23 sensor switch-point voltage	volts

DTCs	P0138 - HO2S12 Circuit High Voltage P0158 - HO2S22 Circuit High Voltage
Monitor execution	continuous
Monitor Sequence	None
Sensors OK	rear HO2S heaters OK
Monitoring Duration	10 seconds to register a malfunction

Entry Condition	Minimum	Maximum
Inferred Stream 2/3 HO2S Temperature	400 °F
Sensor(s) 2/3 HO2S heater-on time	90 seconds
Voltage at sensor 2 HO2S connector	11.0 Volts
Battery Voltage	11.0 Volts	18.0 Volts

> 1.1 volts for 10 seconds for over voltage test

DTCs	P2A01 HO2S12 Circuit Range/Performance (Bank 1 Sensor 2) P2A04 HO2S22 Circuit Range/Performance (Bank 2 Sensor 2)
Monitor execution	continuous
Monitor Sequence	None
Sensors OK	rear HO2S heaters OK, no rear HO2S shorted to ground malfunction
Monitoring Duration	10 seconds to register a malfunction

Entry Condition	Minimum	Maximum
Inferred Stream 2 HO2S Temperature	400 °F
Sensor 2 HO2S heater-on time	90 seconds
Voltage at sensor 2 HO2S connector	11.0 Volts
Battery Voltage	11.0 Volts	18.0 Volts

< -0.2 volts for 10 seconds for out of range low test

DTCs	P0137 HO2S12 Circuit Low Voltage (Bank 1 Sensor 2) P0157 HO2S22 Circuit Low Voltage (Bank 2 Sensor 2)
Monitor Execution	Continuous
Monitor Sequence	None
Sensors OK	rear HO2S heaters OK, no rear HO2S out of range low malfunction, no rear HO2S functional DTCs
Monitoring Duration	10 seconds to register a malfunction

Entry Condition	Minimum	Maximum
Closed Loop
Inferred Stream 2 HO2S Temperature	680 °F	1290 °F (short to ground)
Inferred Stream 2 HO2S Element Temperature (applicable only if Stream 2 HO2S Heater Impedance Monitor is enabled)	480 °F
Time Stream 2 HO2S inferred element temperature within 10% of the predicted steady state temperature (applicable only if Stream 2 HO2S Heater Impedance Monitor is enabled)	1 second
Sensor 2 HO2S heater-on time	60 seconds
All injectors on (no Decel Fuel Shut Off)
Not commanding lean lambda due to torque reduction
Not requesting enrichment due to catalyst reactivation following decel fuel shut off
Sensor 2 HO2S voltage (open circuit voltage fault band): Conti-Moto CBP-A2 PCM Other PCMs	-0.05 Volts 0.30 Volts	0.05 Volts 0.50 Volts
Sensor 2 HO2S voltage (circuit shorted to ground voltage fault band)	-1.00 Volts	0.06 Volts
Voltage at sensor 2 HO2S connector	11.0 Volts
Battery Voltage	11.0 Volts	18.0 Volts

HO2S Circuit Open: > 1 M ohms, fault counter > 14 (200 msec test every 500 msec check) HO2S Circuit Shorted to ground: < 10 ohms, fault counter > 17 (100 msec test every 500 msec check)

Rear HO2S Decel Fuel Shut Off Response Test (2009 MY+) 

The catalyst monitor tracks and uses the length of the rear HO2S signal. The rear HO2S is also known as the Catalyst Monitor Sensor (CMS). As the catalyst ages, air/fuel fluctuations begin to break through the catalyst and the length of this signal increases. Eventually the length of the CMS signal becomes long enough to identify a failure for the catalyst monitor.

When an HO2S sensor degrades, it's response to air/fuel fluctuations slows down. The effect of a slow rear HO2S sensor on the catalyst monitor is to reduce the length of the signal. A slow CMS sensor, therefore, may cause the catalyst monitor to incorrectly pass a failed catalyst. The purpose of the Rear DFSO Response diagnostic is to ensure the catalyst monitor has a valid CMS sensor with which to perform the catalyst monitor diagnostic. The monitor is set to trigger at the level of degradation that will cause the catalyst monitor to falsely pass a malfunction threshold catalyst.

The OBD-II regulations require this monitor to utilize Decel Fuel Shut Off (DFSO). Ford plans to aggressively use DFSO starting in the 2009 MY on many applications to improve fuel economy. The DFSO rear O2 response test will be phased in coincident with this feature.

The main part of the test is the measured rich to lean response rate. It is determined by a "slew" rate calculation which determines the rich to lean slope of the sensor during a Decel Fuel Shut Off (DFSO) event which occurs during closed pedal at vehicle speeds higher than 28 mph. The calculation for the slew rate (mV/sec) is illustrated below.

Linear interpolation is performed to calculate the Slew Rate.

1. For 2010 MY and earlier, interpolate between points P1 and P2 to determine the time at which the rich limit threshold of 0.6 volts was crossed. For 2011MY and beyond, capture the time at T3 at which the rich limit threshold of 0.6 volts was crossed.
2. For 2010 MY and earlier, interpolate between points P3 and P4 to determine the time at which the lean limit threshold of 0.2 volts was crossed. For 2011MY and beyond, capture the time at T4 at which the lean limit threshold of 0.2 volts was crossed.
3. Use the times and the thresholds to calculate the slope or "slew rate" of the CMS sensor from 0.6 to 0.2 volts.

Diagnostic Data Acquisition Event Plot is a schematic of what happens when the pedal is closed and the engine enters DFSO.

The top half of the graph shows the following signals:

• Closed pedal timer (ego_dcms_cptmr).
• PPS (Pedal Position Sensor)
• INJON (# of fuel injectors turned on)

The bottom half of the graph shows a CMS signal with black lines and a "Tx" number representing all of the points of interest where the monitor captures data.

The monitor measures the CMS Rich to Lean slew rate during a DFSO event. The CMS voltage must be rich prior to the injector cut for a valid measurement event. Each fuel cut can only yield 1 valid event. The monitor will complete after 3 valid events. Additional valid event results will be stored and applied over the next drive cycle if necessary for monitor completion.

The slope or slew rate of the CMS sensor going from rich to lean is a negative number with the units of mVolts/sec. The measured slew rate changes as an O2 sensor degrades, but it will also change as a function of catalyst oxygen storage/age; therefore, the slew rate is normalized using an offset based on catalyst oxygen storage/age. The catalyst oxygen storage/age is calculated by integrating the level of oxygen mass in the exhaust stream from the time the injectors turn off to the time where the slew rate calculation begins. The fault line (red line in the chart below) is calibrated to 80% of the fault distribution for various levels of oxygen storage/catalyst age. As shown below, the integrated oxygen mass becomes smaller with catalyst age.

The final output of the monitor = the measured slew rate - normalized fault line, therefore, any positive number will represent a fault. For the step change logic the fault threshold will represent 50% of the failed distribution (~ 0.3).

The delayed response part of the test indicates that the sensor is stuck in range. The code sets if the sensor can't get above a calibrated rich or lean voltage prior to a calibrated time out period. This time out must happen three times in a row to set the fault. If it happens once or twice and then the response monitor completes, the counter will be reset and the sensor will have to fail 3 times in a row to again set the DTC.

Due to the fact that intrusively driving the CMS sensor rich will cause driveability and emission concerns, there are other several condition counters that have to fail prior to intrusively forcing the sensor to go rich. The sequence of events to get to the rich failure is shown below:

• Initially, in order to avoid excess emissions, the monitor will only run if the CMS voltage is rich (> 0.6 volts) or CMS sensor is transitioning from lean to rich (large positive slope. 0.2).
  • Successive failures are counted up; when the count exceeds 5 to 10 failures the monitor will now intrusively force rich fuel to run the test.
• In order to avoid a driveability issues as a result of a lean shifted bank, the first phase of intrusive control has a short time out (1 to 2 seconds).
  • Successive failures are counted up; when the count exceeds 3 failures the monitor will now intrusively force rich fuel to failure or a rich sensor.
• All controllable measures have failed to force the sensor to switch, so the strategy will drive rich until the sensor switches or the failure time out is exceeded (5 to 10 seconds).
  • Successive failures are counted up; when the count exceeds 3 failures the monitor will now set a fault (P013E for bank 1 or P014A for bank 2).

If the sensor is stuck rich (can't get lean) the fault procedure is:

• While the injectors remain off, the sensor must get lean (<0.1 volts) prior to the failure time which must be set to account for a green catalyst (5 to 10 seconds).
  • Successive failures are counted up; when the count exceeds 3 failures the monitor will now set a fault (P013E for bank 1 or P014A for bank 2).

EWMA Fault Filtering 

The EWMA logic incorporates several important CARB requirements. These are:

• Fast Initial Response (FIR): The first 4 tests after a battery disconnect or code clear will process unfiltered data to quickly indicate a fault. The FIR will use a 2-trip MIL. This will help the service technician determine that a fault has been fixed.
• Step-change Logic (SCL): The logic will detect an abrupt change from a no-fault condition to a fault condition. The SCL will be active after the 4th DCMS monitor cycle and will also use a 2-trip MIL. This will illuminate the MIL when a fault is instantaneously induced.
• Normal EWMA (NORM): This is the normal mode of operation and uses an Exponentially Weighted Moving Average (EWMA) to filter the DCMS test data. It is employed after the 4th DCMS test and will illuminate a MIL during the drive cycle where the EWMA value exceeds the fault threshold. (1 trip MIL).

DTCs	P013A - O2 Sensor Slow Response - Rich to Lean (Bank 1 Sensor 2) P013C - O2 Sensor Slow Response - Rich to Lean (Bank 2 Sensor 2) P013E - O2 Sensor Delayed Response - Rich to Lean (Bank 1 Sensor 2) (sensor stuck in range) P014A - O2 Sensor Delayed Response - Rich to Lean (Bank 2 Sensor 2) (sensor stuck in range)
Monitor Execution	Once per driving cycle, after 3 DFSO events.
Monitor Sequence	> 30 seconds time in lack of movement test (UEGO only), > 30 seconds time in lack of switch test, front HO2S/UEGO response test completed, HO2S 2 and 3 functional tests completed, HO2S/UEGO heater voltage and current checks completed, FAOS monitor system bias maturity met (UEGO applications only)
Sensors OK	ECT, IAT, MAF, VSS, TP, ETC, FRP, EGR, VCT, VMV/EVMV, CVS, FTP, CKP, CMP, ignition coils, injectors, no misfire DTCs, no system failures affecting fuel, no EVAP gross leak failure, UEGO heaters OK, rear HO2S heaters OK, no "lack of switching" malfunction, no "lack of movement" malfunction, no UEGO circuit malfunction, no rear stream 2 HO2S circuit malfunction, no rear stream 2 HO2S functional DTCs, Not performing CSER spark retard. Flex fuel composition not changing. No intrusive EGO monitors running.
Monitoring Duration	3 DFSO events, 450 seconds on the FTP.

Entry Condition	Minimum	Maximum
Air Mass	0.5	6
Vehicle Speed		90
Inlet Air Temp		140 °F
Engine Coolant Temp	155 °F	240 °F
Catalyst Temperature (Inferred)	800 °F	1600 °F
Rear Ego Tip Temperature (Inferred)	800 °F
Fuel Level	15%
Fuel In Control	-3%	3%
Adaptive Fuel Within Limits	-3%	3%
Battery Voltage	11.0 Volts	18.0 Volts
Rich Voltage on downstream CMS sensor(s)	0.6 Volts
Rich Voltage on upstream HEGO / UEGO sensor(s)	0.45 Volts (HEGO)	1 UEGO)

Rich to lean slew rate thresholds:  Normal Threshold = > 0.0 mV/sec Fast Initial Response Threshold = > 0.0 mV/sec Step Change Threshold = > 0.3 mV/sec NOTE: Note that the thresholds use a normalized offset and the threshold is set at "zero".

Successive failures are counted up (5 to 10 faults). Monitor will now intrusively force rich fuel to run the test. Intrusive controls will time out based on driveability (1 to 2 sec). Successive driveability failures are counted up (3 faults). Intrusive controls will now time out at a slower time (5 to 10 sec) and count a fault. After 3 faults are counted, a DTC is set.

Monitor ID	Test ID	Description	Unit
$02	$85	HO2S12 Fuel Shut off Rich to Lean Response Rate (P013A)	mV/sec
$02	$86	HO2S12 Fuel Shut off Rich to Lean Response Time (P013E)	msec
$06	$85	HO2S22 Fuel Shut off Rich to Lean Response Rate (P013C)	mV/sec
$06	$86	HO2S22 Fuel Shut off Rich to Lean Response Time (P014A)	msec

Rear HO2S Heaters 

The HO2S heaters are monitored for proper voltage and current. A HO2S heater voltage fault (open, shorted to ground, or shorted to battery) is determined by turning the heater on and off and looking for corresponding voltage change in the heater output driver circuit in the PCM.

Beginning 2014MY, some applications have rear HO2S that uses impedance feedback heater controller to control impedance to a corresponding element temperature. The HO2S impedance feedback heater controller keeps the HO2S heater at constant impedance (Bosch LSF-X4: 220 ohms, NTK S2.01: 150 ohms), which corresponds to a temperature (Bosch LSF-X4: 780 deg C, NTK S2.01: 650 deg C). The impedance of the HO2S decreases as the sensor temperature increases. After a cold start, the HO2S heater ramps up to the maximum duty cycle to heat the sensor. After a few seconds, the measured impedance will start to decrease and when the target value is crossed, the heater goes into closed loop heater control to maintain the sensor at the target impedance.

The "HO2S Heater Temperature Control Monitor" tracks the time at the maximum duty cycle during the open loop sensor warm up phase. If the measured impedance does not come down to the target value to allow the system to transition from open loop heater control to closed loop heater control within a specified time, then a P0036/P0056 fault code is set. This monitor also sets a malfunction when the closed loop heater controller reaches a maximum or minimum duty cycle for a period of time indicating that the controller is no longer able to maintain the target impedance. However, if the exhaust temperature is high enough that the sensor will be below the target impedance even with no heat, then this monitor is disabled.

A separate current-monitoring circuit monitors heater current once per driving cycle. This monitor normally runs after the HO2S heaters have been on for some time and inferred to have been adequately warm. However, on applications that use HO2S impedance feedback heater controller, it can also run intrusively. When the HO2S impedance indicates cold, but the heater is inferred to have been adequately warm, the current monitor is forced to run intrusively prior to the completion of the heater temperature control monitor. If the current measurement falls below or above a calibratable threshold, the heater is assumed to be degraded or malfunctioning.

Beginning 2012MY, some PCMs do not have a separate heater current-monitoring circuit (without shunt resistors that can directly measure the current through the HEGO heaters). For applications that do not have a heater current-monitoring circuit and also do not use HO2S impedance feedback heater controller, the sensor heater performance is monitored by the "HO2S Heater Impedance Monitor". The HO2S heater impedance monitor measures the HO2S internal impedance, validates the measurement, and then compares the validated internal impedance to an internal impedance threshold. If the validated internal impedance exceeds the threshold, then the monitor fault counter increments once. If the fault counter exceeds the total number of valid internal impedance measurements required, a HO2S heater control circuit range/performance malfunction (P00D2/P00D4) will be set.

The HO2S heater impedance monitor runs once per trip; however, it can also be forced to run intrusively. When the heater is inferred to have been adequately warm, but the HO2S sensor is suspected to be cold because the HO2S voltage falls inside the suspected open HO2S circuit voltage fault band or inside the suspected HO2S circuit shorted to ground voltage fault band, a HEGO sensor circuit or HEGO heater malfunction is suspected. To differentiate HO2S signal circuit failures from a degraded/malfunctioning heater or normal FAOS control, the HO2S heater impedance monitor is forced to run intrusively after the heater voltage test and the HO2S open/short to ground circuit diagnostics had ran and indicated no malfunction.

Any corrosion in the harness wiring, connector, or increase in the sensor heater element resistance will result in an overall increase in the heater circuit resistance, causing the HO2S impedance to increase. The impedance is dependent on the HO2S element temperature and the voltage at the connector. As the HO2S element temperature increases, the impedance decreases. Furthermore, as the voltage at the connector increases, the sensor impedance decreases. Hence, the impedance threshold for the HO2S heater impedance monitor is a function of the inferred HO2S element temperature and the voltage at the connector.

On the other hand, applications that use HO2S impedance feedback heater controller and also do not have a separate heater current-monitoring circuit, a degraded or malfunctioning HO2S heater is detected by the "HO2S Heater Temperature Control Monitor." This monitor would call the malfunction after the heater voltage test and HO2S circuit diagnostics had run first and indicated no malfunction.

DTCs Sensor 2	P0036 - HO2S12 Heater Control Circuit, Bank 1 P0056 - HO2S22 Heater Control Circuit, Bank 2 P0141 - O2 Sensor Heater Circuit, Bank 1 P0161 - O2 Sensor Heater Circuit, Bank 2 P0054 - HO2S Heater Resistance, Bank 1 P0060 - HO2S Heater Resistance, Bank 2 P00D2 - HO2S Heater Control Circuit Range/Performance (Bank 1, Sensor 2) P00D4 - HO2S Heater Control Circuit Range/Performance (Bank 2, Sensor 2)
DTCs Sensor 3	P0147 - O2 Sensor Heater Circuit, Bank 1 P0167 - O2 Sensor Heater Circuit, Bank 2 P0055 - HO2S Heater Resistance, Bank 1 P0061 - HO2S Heater Resistance, Bank 2
Monitor execution	once per driving cycle for heater current monitor and HO2S heater impedance monitor, continuous for voltage monitoring and HO2S heater temperature control monitoring
Monitor Sequence	Heater current monitor: Stream 1 HO2S/UEGO response test completed (2010 MY and earlier), Stream 2 and 3 HO2S functional tests completed (2010 MY and earlier), HO2S/UEGO heater voltage check completed. HO2S heater temperature control monitor: Stream 2 HO2S heater voltage check completed, Stream 2 HO2S circuit check completed, intrusive heater current monitor completed (if applicable). HO2S heater impedance monitor: Stream 2 HO2S heater voltage check completed, Stream 2 HO2S circuit check and test time slice completed.
Sensors OK	Heater current monitor: no HO2S/UEGO heater voltage DTCs. HO2S heater temperature control monitor: no rear HO2S circuit malfunction, no rear HO2S out of range low malfunction, no rear HO2S heater circuit malfunction, no HO2S heater current monitor DTCs. HO2S heater impedance monitor: rear HO2S heaters OK, no rear HO2S out of range low malfunction, no rear HO2S functional DTCs, no rear HO2S circuit malfunction.
Monitoring Duration	< 10 seconds for heater voltage check, < 5 seconds for heater current check, >= 30 seconds for the HO2S heater temperature control monitor to register a malfunction, < 11 seconds for HO2S heater impedance test.

Entry Condition	Minimum	Maximum
Heater Voltage Test:
Inferred HO2S 2/3 Temperature	400 °F	1400 °F
Battery Voltage	11.0 Volts	18.0 Volts
Heater Current Test:
Inferred HO2S 2 Temperature	250 °F	1400 °F
Inferred HO2S 3 Temperature	250 °F	1400 °F
HO2S 1/2/3 heater-on time	30 seconds
Engine RPM		5000 rpm
Battery Voltage	11.0 Volts	18.0 Volts
HO2S Heater Temperature Control Monitor:
Heater voltage test completed
Stream 2 HO2S circuit check completed
Intrusive heater current monitor completed (if applicable)
Battery Voltage	11.0 Volts	18.0 Volts
HO2S Heater Impedance Test:
Inferred Stream 2 HO2S Temperature	680 °F
Inferred Stream 2 HO2S Element Temperature	480 °F	1020 °F
Time Stream 2 HO2S inferred element temperature within 10% of the predicted steady state temperature	1 second
Sensor 2 HO2S heater-on time	60 seconds
All injectors on (no Decel Fuel Shut Off)
Not commanding lean lambda due to torque reduction
Not requesting enrichment due to catalyst reactivation following decel fuel shut off
Sensor 2 HO2S voltage (open circuit voltage fault band- intrusive test only): Conti-Moto CBP-A2 PCM Other PCMs	-0.05 Volts 0.30 Volts	0.05 Volts 0.50 Volts
Sensor 2 HO2S voltage (circuit shorted to ground voltage fault band intrusive test only)	-1.00 Volts	0.06 Volts
Voltage at sensor 2 HO2S connector	11.0 Volts
11.0 Volts		18.0 Volts

Monitor ID	Test ID	Description	Units
$42	$81	HO2S12 Heater Current (P0054)	Amps
$46	$81	HO2S22 Heater Current (P0060)	Amps
$43	$81	HO2S13 Heater Current (P0055)	Amps
$47	$81	HO2S23 Heater Current (P0061)	Amps
$42	$82	O2S12 Heater Impedance (P00D2)	kOhm
$46	$82	O2S22 Heater Impedance (P00D4)	kOhm