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DTC P0135: 1/1 O2 Sensor Heater Failure: Testing

NOTE: 1/1 HO2S may also be referred to as an upstream oxygen sensor. On 2.4L, 1/1 HO2S is located on exhaust manifold flange. On 3.3L and 3.8L, 1/1 HO2S is located on right exhaust manifold flange (manifold closest to firewall).
  1. Turn ignition on. Using scan tool, read DTCs. If Good Trip counter is displayed for DTC P0135 and displayed count is "0", go to next step. If Good Trip counter is not displayed for DTC P0135 or displayed count is not "0", go to step  3.
  2. Turn ignition off. Allow HO2S to cool down for about 8 minutes. Turn ignition on. Using scan tool in SENSOR mode, monitor 1/1 HO2S voltage until voltage stabilizes at .4-.6 volt. Using scan tool, actuate HO2S HEATER TEST and monitor 1/1 HO2S voltage for 2 minutes. If voltage stays at .4-.6 volt, go to next step. If voltage does not stay at .4-.6 volt, go to step  8.
  3. Turn ignition off. Allow HO2S to cool down to room temperature. Disconnect 1/1 HO2S connector. Measure resistance between Brown/White and Brown/Light Green wires at 1/1 HO2S connector (component side). If resistance is not 2-7 ohms, replace 1/1 HO2S. If resistance is 2-7 ohms, 1/1 HO2S heater element is okay. Go to next step.
  4. Ensure ignition is off. Disconnect PCM connectors. PCM is located on left side of engine compartment, near front of battery. Measure resistance of Brown/Light Green wire between 1/1 HO2S harness connector and terminal No. 18 at PCM C1 harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Brown/Light Green wire.
  5. Measure resistance between ground and Brown/Light Green wire at 1/1 HO2S harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Brown/Light Green wire between PCM and 1/1 HO2S.
  6. Ensure ignition is off. Reconnect PCM connectors. Turn ignition on. Using scan tool, actuate HO2S HEATER TEST. Measure voltage between ground and Brown/White wire at 1/1 HO2S wiring harness connector. If voltage is more than 11 volts, go to next step. If voltage is 11 volts or less, repair open in power circuit (Brown/White wire) to 1/1 HO2S heater. See WIRING DIAGRAMS article.
  7. At this time, PCM is assumed to be defective. Replace PCM. Program the new PCM. See PROGRAMMING .
  8. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor parameters related to DTC while wiggling connectors and wiring harness. If value changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused value to change. If value does not change, review Freeze Frame data using scan tool. Attempt to duplicate condition that caused DTC to set. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.
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