Advanced Diagnostics

Advanced Diagnostics-DTC P0134: Air Fuel Ratio (A/F) Sensor (Sensor 1) Heater System Malfunction

General Description






The air/fuel ratio (A/F) sensor (sensor 1) is activated by warming the element with a heater and by maintaining a steady high temperature to accurately calculate the air/fuel ratio. If the heater does not properly heat the element, the A/F sensor does not activate, and the exhaust emissions deteriorate. The powertrain control module (PCM) monitors the A/F sensor internal resistance.

1. When the A/F sensor does not activate for a set time after the A/F sensor heater is turned on (with high A/F sensor internal resistance), a malfunction of the A/F sensor heater is detected, and a DTC is stored.
2. When the A/F sensor heater cycles ON and OFF for a set time, and the resistance remains high when the heater is ON, a malfunction of the A/F sensor heater is detected, and a DTC is stored.

Monitor Execution, Sequence, Duration, DTC Type, OBD Status






Enable Conditions






Malfunction Threshold

- Malfunction determination 1 - From start up
The A/F sensor (sensor 1) internal resistance value [AF SENSOR IMPEDANCE] is 120 Ohms or more for at least 40*1 (90)*2 seconds right after the engine starts.

- Malfunction determination 2 - Hot
The A/F sensor (sensor 1) internal resistance value [AF SENSOR IMPEDANCE] is 250 Ohms or more for at least 1.0 second.

Possible Cause

NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.

- A/F sensor (sensor 1) heater failure
- A/F sensor (sensor 1) element failure

Confirmation Procedure

With the HDS
None.

With the Driving Pattern
Start the engine, and let it idle for at least 1 minute. When engine coolant temperature [ECT SENSOR 1] is 5 °F (-15 °C) or less, let the engine idle for at least 5 minutes.

Diagnosis Details

Conditions for setting the DTC
When a malfunction is detected during the first drive cycle, a Pending DTC is stored in the PCM memory. If the malfunction returns in the next (second) drive cycle, the MIL comes on and a Confirmed DTC and the freeze data are stored.

Conditions for clearing the DTC
The MIL is cleared if the malfunction does not return in three consecutive trips in which the diagnostic runs. The MIL, the Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command or by disconnecting the battery.