DTC P0134: Air/Fuel Ratio (A/F) Sensor (Sensor 1) Heater System Malfunction (L4)

General Description 

Courtesy of HONDA, U.S.A., INC.

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, OBD Status 

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
OBD Status	PASSED/FAILED/NOT COMPLETED (STILL TESTING)

*: Malfunction determination 1

**: Malfunction determination 2

*1: USA and Canada models and 2017 on and after Mexico models

*2: 2015 - 2016 Mexico models

Enable Conditions 

Condition	Minimum	Maximum
12 volt battery voltage [BATTERY]	10.5 V	-
Fuel feedback	Other than during fuel cut-off operation
No active DTCs set (prevents monitor from running)* 3	P0135, P0300, P0301, P0302, P0303, P0304, P0351, P0352, P0353, P0354, P1157, P1172, P2195, P2238, P2252
No active DTCs set (prevents monitor from running)* 4	P0135, P0300, P0301, P0302, P0303, P0304, P0351, P0352, P0353, P0354, P1172, P2195, P2237, P2238, P2252

*3: 2015 - 2016 models

*4: 2017 model on and after

[ ]: HDS Parameter

Malfunction Threshold 

• Malfunction determination 1 - From start up

  The A/F sensor (sensor 1) internal resistance value [AF SENSOR IMPEDANCE] is 120 Ω 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 Ω 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 

Operating Condition 

Start the engine, and let it idle for at least 1 minute. When engine coolant temperature [ECT SENSOR 1] is 5 °F (-15 °C)* 1 (14 °F (-10 °C))* 2 or less, let the engine idle for at least 6 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.