DTC Advanced Diagnostics: P0135 (2.0L Engine) (2024 2025)
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 seconds 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
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
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, the freeze data, and the on-board snapshot 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, the freeze data, and the on-board snapshot can be cleared with the scan tool clear command.