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Home › Dodge and Ram › 2001 › Dakota R/T, 2D Pickup › Repair and Diagnosis › Engine Performance › System › Engine Controls - Self-Diagnostics › Diagnostic Tests › DTC P0136: 1/2 O2 Sensor Heater Circuit Malfunction › Testing

DTC P0136: 1/2 O2 Sensor Heater Circuit Malfunction: Testing

  1. Turn ignition on with engine off. Using scan tool, check for DTCs. If DTC SPECIFIC GOOD TRIP counter is displayed and equal to zero, go to next step. If DTC SPECIFIC GOOD TRIP counter is not displayed and equal to zero, go to step  8.
  2. Turn ignition off. Check for open or defective fuse "U" (20-amp). This is the fuse for oxygen sensor downstream heater relay. Fuse "U" is located in Power Distribution Center (PDC). PDC is located at driver's side front corner of engine compartment, near battery. If fuse "U" is open or defective, go to next step. If fuse "U" is not open or defective, go to step  4.
  3. Ensure fuse "U" is removed from PDC. Remove oxygen sensor downstream heater relay from PDC. See Figure. Note cavities in PDC for oxygen sensor downstream heater relay. Using ohmmeter, measure resistance between ground and oxygen sensor downstream heater relay cavity No. 86 (Orange/Dark Green wire) in Power Distribution Center (PDC). If resistance is 5 ohms or more, replace fuse "U" and perform TEST VER-5A . If resistance is less than 5 ohms, repair short to ground on Orange/Dark Green wire between fuse "U" in and oxygen sensor downstream heater relay in PDC. Replace fuse "U" and perform TEST VER-5A .
  4. Remove oxygen sensor downstream heater relay from PDC. See Figure. Note which terminals on oxygen sensor downstream heater relay correspond with cavities in PDC. Using ohmmeter, measure resistance between oxygen sensor downstream heater relay terminals that correspond with cavities No. 85 and 86 in PDC. If resistance is less than 100 ohms, go to next step. If resistance is 100 ohms or more, replace oxygen sensor downstream heater relay. Perform TEST VER-5A .
  5. Ensure fuse "U" is removed from PDC. Using ohmmeter, measure resistance of Orange/Dark Green wire between oxygen sensor downstream heater relay cavity No. 86 and fuse "U" in PDC. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open on Orange/Dark Green wire between fuse "U" and oxygen sensor downstream heater relay in PDC. Perform TEST VER-5A .
  6. Ensure ignition is off. Disconnect PCM connectors. PCM is located at passenger's side front corner of engine compartment on inner fender panel. Using ohmmeter, measure resistance of Dark Green/Black wire between oxygen sensor downstream heater relay cavity No. 85 in PDC for and PCM connector C3 terminal No. 9. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open on Dark Green/Black wire between PCM and oxygen sensor downstream heater relay in PDC. Perform TEST VER-5A .
  7. Ensure PCM connectors are still disconnected. Using ohmmeter, measure resistance between ground and oxygen sensor downstream heater relay cavity No. 85 (Dark Green/Black wire) in PDC. If resistance is 5 ohms or more, replace PCM. Perform TEST VER-5A . If resistance is less than 5 ohms, repair short to ground on Dark Green/Black wire between PCM and oxygen sensor downstream heater relay in PDC. Perform TEST VER-5A .
  8. Start engine and allow engine to idle. Wiggle wiring harness and connectors between PCM, fuse "U" (20-amp) and oxygen sensor downstream heater relay while noting DTC SPECIFIC GOOD TRIP counter. PCM is located at passenger's side front corner of engine compartment on inner fender panel. Fuse "U" is for oxygen sensor downstream heater relay is located in Power Distribution Center (PDC). Oxygen sensor downstream heater relay is located in PDC. See Figure. PDC is located at driver's side front corner of engine compartment, near battery. If DTC SPECIFIC GOOD TRIP counter does not change to zero while wiggling wiring harness and connectors, go to next step. If DTC SPECIFIC GOOD TRIP counter changes to zero while wiggling wiring harness and connectors, repair wiring or connectors between PCM, fuse "U" and oxygen sensor downstream heater relay as necessary. Perform TEST VER-5 .
  9. Shut engine off. Ensure ignition is off. Disconnect PCM connectors. Inspect PCM connectors for corroded, pushed out, miswired or damaged terminals. Inspect wiring harness between PCM, fuse "U" and oxygen sensor downstream heater relay for any possible intermittent problems. Also, check for related Technical Service Bulletins (TSBs). If terminals are not corroded, pushed out or damaged and wiring harness is okay, test is complete. If terminals are corroded, pushed out or damaged or wiring harness is damaged, repair as necessary. Perform TEST VER-5 .
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