DTC P0136: 1/2 O2 Sensor Heater Circuit Malfunction (4.0L With CALIF. Emissions): Testing
NOTE:
1/2 HO2S is located in front exhaust pipe below front mini-catalytic converter and may also be referred to as a downstream oxygen sensor.
- Turn ignition on. Using scan tool, check for DTCs. If GOOD TRIP counter is displayed for DTC P0136 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0136 or displayed count is not "0", go to step 9 .
- Turn ignition off. Remove and inspect fuse No. 16 (10-amp) from Power Distribution Center (PDC) located in right side of engine compartment, next to battery. See Figure . If fuse is okay, go to step 4 . If fuse is blown, go to next step.
- Remove HO2S downstream heater relay from PDC. See Figure . Measure resistance between ground and terminal B11 (Orange/Dark Green wire) at HO2S downstream heater relay socket in PDC. See Figure . If resistance is 5 ohms or more, circuit is okay. Replace fuse. If resistance is less than 5 ohms, repair short to ground in Orange/Dark Green wire. Replace fuse.
- Remove HO2S downstream heater relay from PDC. See Figure . Measure resistance between terminals No. 85 and 86 at downstream heater relay. See Fig 1 . If resistance is 100 ohms or less, go to next step. If resistance is more than 100 ohms, replace relay.
- Measure resistance of Orange/Dark Green wire between terminal B11 at HO2S downstream heater relay socket in PDC and terminal No. 16 at fuse holder for fuse No. 16 in PDC. See Figure . If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Orange/Dark Green wire.
- Ensure ignition is off. Disconnect Powertrain Control Module (PCM) connectors. PCM is located on firewall in right rear corner of engine compartment. Measure resistance of Red/Yellow wire between terminal B15 at HO2S downstream heater relay socket in PDC and terminal C9 at PCM C3 harness connector. See Figure and Figure . If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Red/Yellow wire.
- Measure resistance between ground and terminal B15 (Red/Yellow wire) at HO2S downstream heater relay socket in PDC. See Figure . If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Red/Yellow wire. See WIRING DIAGRAMS article.
- At this time, PCM is assumed to be defective. Replace PCM.
- It is assumed that there is an intermittent problem with wiring harness and/or connectors. Visually inspect all related connectors and wiring harness for any possible problems. Also, check for any related technical service bulletins.