O2 Sensor 1/1 Heater Circuit High
P0135 - O2 SENSOR 1/1 HEATER CIRCUIT HIGH
When Monitored and Set Condition
- When Monitored: Engine Running and Heater duty cycle greater than 0%.
- Set Condition: O2 Heater Temperature does not reach 575° C (959° F) within 90 seconds during monitoring conditions. Two Trip Fault.
Diagnostic Test
1. PRE-DIAGNOSTIC CHECK OUT
NOTE: Always perform diagnostics with a fully charged battery.
NOTE: Check connectors - Clean/repair as necessary. Poor pin to terminal connections can set DTCs.
NOTE: Check for applicable TSBs related to the problem.
Turn the ignition on.
With the DRB III(R), read PCM DTCs.
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors. Repair as necessary.
Perform this procedure prior to symptom diagnosis.
Continue
- Go To 2
2. CHECK FOR CURRENT DTC
NOTE: If the PCM detects and stores a DTC, the PCM also stores the engine/vehicle operating conditions under which the DTC was set. Some of these conditions are displayed on the DRB III(R) at the same time the DTC is displayed.
NOTE: Before erasing stored DTCs, record these conditions. Attempting to duplicate these conditions may assist when checking for an active DTC.
Turn the ignition on.
With the DRB III(R), erase PCM DTCs.
NOTE: It maybe necessary to road test the vehicle for this DTC to set.
With the DRB III(R), read PCM DTCs.
Did this DTC set again?
Yes
- Go To 4
No
- Go To 3
3. O2 SENSOR HEATER OPERATION
Turn the ignition off.
NOTE: Allow the O2 Sensor to cool down before continuing the test. Raising the hood may help in reducing under hood temperatures.
Connect a jumper wire between ground and the Oxygen Sensor Heater Control circuit at the PCM harness connector leaving the harness connector connected to the PCM.
Turn the ignition on.
With the DRB III(R), monitor O2 Sensor voltage for at least 2 minutes.
CAUTION: Remove the jumper wire after this Step is complete.
Does the voltage stay above 0.47 volt?
Yes
- Go To 4
No
- Go To 7
4. O2 HEATER ELEMENT
NOTE: Check the Engine Control Fuse 2 in the Relay Control Module. If it is open, multiple DTCs will be set in the PCM. Determine the cause of the open fuse before continuing using the wiring diagrams/schematics as a guide.
Turn the ignition off.
NOTE: Allow the O2 Sensor to cool down to room temperature. Raising the hood may help in reducing under hood temperatures.
Disconnect the O2 Sensor harness connector.
NOTE: Check connectors - Clean/repair as necessary.
Measure the resistance of the O2 Sensor Heater element.
NOTE: O2 Sensor Heater Resistance Specification: 8.5 to 9.5 ohms.
Is the resistance within specifications?
Yes
- Go To 5
No
- Replace the O2 Sensor.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2
5. FUSED ENGINE CONTROL RELAY OUTPUT CIRCUIT OPEN
Turn the ignition on.
Measure the voltage of the O2 Heater Fused Engine Control Relay Output circuit at the O2 Sensor harness connector.
Is the voltage above 10 volts?
Yes
- Go To 6
No
- Repair the O2 Heater Fused Engine Control Relay Output circuit for an open.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2
6. O2 HEATER CONTROL CIRCUIT OPEN
Turn the ignition off.
Disconnect the PCM harness connectors.
NOTE: Check connectors - Clean/repair as necessary.
Measure the resistance of the O2 Heater Control circuit from the O2 Sensor harness connector to the PCM harness connector.
Is the resistance below 5.0 ohms?
Yes
- Replace and program the Powertrain Control Module.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2
No
- Repair the O2 Heater Control circuit for an open.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2
7. INTERMITTENT WIRING AND CONNECTORS
The conditions necessary to set this DTC are not present at this time.
NOTE: Check connectors - Clean/repair as necessary. Poor pin to terminal connections can set DTCs.
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors specific to this DTC. Wiggle the wires while checking for shorts and open circuits.
NOTE: Check for any Technical Service Bulletins that may apply.
Were there any problems found?
Yes
- Repair as necessary.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2
No
- The condition that caused this DTC to set is currently not present. Inspect the related wiring harness for a possible intermittent condition.