DTC Advanced Diagnostics: P0135
DTC P0135:Air/Fuel Ratio (A/F) Sensor (Sensor 1) Heater Circuit Malfunction

General Description

A heater for the sensor element is embedded in the air/fuel ratio (A/F) sensor (sensor 1), and it is controlled and monitored by the powertrain control module (PCM). It is activated and heats the sensor to stabilize and speed up the detection of oxygen content when the exhaust gas temperature is cold. If the A/F sensor (sensor 1) heater output current or voltage is a specified value, the PCM detects a malfunction and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type
Execution
Continuous
Sequence
None
Duration
0.5 second or more
DTC Type
Two drive cycles, MIL on

Enable Conditions
Condition
Minimum
Maximum
12 volt battery voltage [Battery]
8 V
16 V
A/F sensor (sensor 1) heater duty*
4 %
State of the engine
Running
*: Short circuit to power diagnosis
[ ]: HDS Parameter

Malfunction Threshold
Short circuit to power
The A/F sensor (sensor 1) heater output current is 24 A or more while the power stage is on.
Short circuit to ground
The A/F sensor (sensor 1) heater output voltage is 2.74 V or less while the power stage is off.
Open circuit
The A/F sensor (sensor 1) heater output voltage is between 3.26 - 4.7 V while the power stage is off.

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) AFHT line open
A/F sensor (sensor 1) AFHT line short to ground
A/F sensor (sensor 1) AFHT line short to power
A/F sensor (sensor 1) power supply line open
A/F sensor (sensor 1) power supply line short to ground
PGM-FI subrelay FI SUB RLY CL- line open
A/F sensor (sensor 1) failure
PCM internal circuit failure

Confirmation Procedure
Operating Condition
Start the engine, and let it idle.

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.