Code 45 - Rich Exhaust Indication
The ECM supplies a voltage of about .45 volt between circuits 412 and 413. The O2 sensor varies the voltage from 1 volt (rich exhaust) to .10 volt (lean exhaust). The sensor acts like an open sensor circuit and produces no voltage when exhaust temperature is below 600°F (310°C). An open sensor circuit or cold sensor causes open loop operation. Code 45 is set when O2 sensor signal at ECM is above .7 volts for 1 second and time since engine start is 1 minute or more.
NOTE:
The following step numbers refer to the step numbers in the accompanying Flow Chart.
- Grounding diagnostic test terminal with engine running, activates the "Field Service Mode" and allows the ECM to confirm either open or closed loop operation.
- A steady light or "open loop" indicates presence of fault. Grounding circuit 412 causes a low O2 sensor signal voltage. If the ECM and wiring are okay, the ECM should recognize the low voltage, and confirm lean signal by turning "CHECK ENGINE" light for at least 30 seconds.
- Code 45 will not be set by a faulty O2 sensor. Code 45 indicates a rich exhaust and diagnosis should begin with these items: Fuel pressure, leaking injector, HEI shielding, canister purge saturation, coolant sensor, MAP sensor, and TPS intermittent output.