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DTC P0135: O2 Sensor Heater Failure

NOTE: For connector terminal ID, see CONNECTOR IDENTIFICATION . For wiring diagram, see WIRING DIAGRAMS article.
NOTE: Upstream oxygen sensor is referred to as 1/1 O2 sensor in this test and is mounted on the exhaust manifold. Upstream oxygen sensor heater operation is monitored after ignition is turned off and engine cools down. DTC may be stored in Powertrain Control Module (PCM) if no upstream oxygen sensor signal is received when the PCM powers up and oxygen sensor heater. Possible causes are: defective upstream oxygen sensor or heater, defective Auto Shutdown (ASD) relay circuit, or defective connectors or wiring.
  1. Using scan tool, check for DTCs. If global good trip counter is displayed and equal to zero, go to next step. If global good trip counter is not displayed and equal to zero, go to step  3.
  2. Turn ignition on with engine off. With scan tool in SENSOR mode, wait about 3 minutes until upstream oxygen sensor voltage is 4.5 volts. Once upstream oxygen sensor voltage is 4.5 volts, use scan tool in ACTUATOR mode to actuate oxygen sensor heater test while monitoring upstream oxygen sensor voltage for at least 3 minutes. Oxygen sensor heater test may also be referred to as O2 sensor heater test. If upstream oxygen sensor voltage is one volt or less, go to next step. If upstream oxygen sensor voltage is more than one volt, go to step  4.
  3. At this time, conditions for upstream oxygen sensor heater failure does not exist or is an intermittent problem. Using scan tool, read FREEZE FRAME data while attempting to duplicate the condition that caused DTC to be set by paying special attention to the conditions that upstream oxygen sensor heater is monitored. Upstream oxygen sensor heater is monitored when ignition is off and then engine has cooled down. Recheck for DTC P0135: O2 SENSOR HEATER FAILURE. If DTC P0135: O2 SENSOR HEATER FAILURE exists, go to next step. If DTC P0135: O2 SENSOR HEATER FAILURE does not exist, oxygen sensor heater failure no longer exists. Perform TEST VER-5A3 .
  4. Disconnect connector at upstream oxygen sensor. Upstream oxygen sensor is mounted on exhaust manifold. Inspect connector for corroded, pushed out, miswired or damaged terminals. If terminals are not corroded, pushed out, miswired or damaged, go to next step. If terminals are corroded, pushed out, miswired or damaged, repair connector as necessary. Perform TEST VER-5A3 .
  5. Turn ignition on with engine off. Ensure connector is still disconnected at upstream oxygen sensor. Using scan tool in ACTUATOR mode, actuate oxygen sensor heater test.
  6. Using voltmeter, check voltage at terminal No. 2 (Dark Green/Orange wire) on wiring harness side of connector for upstream oxygen sensor while still performing oxygen sensor heater test. If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, repair open circuit on Dark Green/Orange wire from Auto Shutdown (ASD) relay to upstream oxygen sensor. ASD relay is located in power distribution center at driver's side front corner of engine compartment, near battery. Perform TEST VER-5A3 .
  7. Stop oxygen sensor heater test. Using ohmmeter, check resistance of upstream oxygen sensor heater between terminals No. 1 and 2 on oxygen sensor side of connector for upstream oxygen sensor. Terminals No. 1 and 2 are the 2 top terminals on the connector, closest to the release latch on the connector. If resistance is 4-7 ohms, go to next step. If resistance is not 4-7 ohms, replace upstream oxygen sensor. Perform TEST VER-5A3 .
  8. Using ohmmeter, check resistance between ground and terminal No. 1 (Black wire) on wiring harness side of connector for upstream oxygen sensor. If resistance is less than 5 ohms, replace upstream oxygen sensor. Perform TEST VER-5A3 . If resistance is 5 ohms or more, repair open ground circuit on Black wire to upstream oxygen sensor. Perform TEST VER-5A3 .
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