DTC Advanced Diagnostics: P0134
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 (sensor 1) does not activate, and the exhaust emissions deteriorate. The powertrain control module (PCM) monitors the A/F sensor (sensor 1) internal resistance.
1.
When the A/F sensor (sensor 1) does not activate for a set time after the A/F sensor (sensor 1) heater is turned on (with high A/F sensor (sensor 1) internal resistance), a malfunction of the A/F sensor (sensor 1) heater is detected, and a DTC is stored.
2.
When the A/F sensor (sensor 1) 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 (sensor 1) heater is detected, and a DTC is stored.

Monitor Execution, Sequence, Duration, DTC Type
Execution
Continuous
Sequence
None
Duration*1
40 seconds or more*, 1.0 second or more**
Duration*2
90 seconds or more*, 1.0 second or more**
DTC Type
Two drive cycles, MIL on
*: Malfunction determination 1
**: Malfunction determination 2
*1: USA and Canada models
*2: Mexico models

Enable Conditions
Condition
Minimum
Maximum
12 volt battery voltage [BATTERY]
10.5 V
–
Fuel feedback
Other than during fuel cut-off operation
A/F sensor (sensor 1) heater
ON
State of the engine
Running
Other
Other than initial engine start
[ ]: HDS Parameter

Malfunction Threshold
Malfunction determination 1 - From start up
The A/F sensor (sensor 1) internal resistance value [AF SENSOR IMPEDANCE] is 200 ? or more for at least 40 seconds*1 (90 seconds)*2 right after the engine starts.
Malfunction determination 2 - Hot
The A/F sensor (sensor 1) internal resistance value [AF SENSOR IMPEDANCE] is 270 ? 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
A/F sensor (sensor 1) VS line open

Confirmation Procedure
Operating Condition
Start the engine, and let it idle for at least 1 minute. When engine coolant temperature [ECT SENSOR 1] is less than 5 °F (-15 °C), let the engine idle for at least 7 minutes.

With the HDS
None.

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 12 volt battery.