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 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 current is not a set value, or the heater is overheated, the PCM detects a malfunction and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type

Execution	Continuous
Sequence	None
Duration	4 seconds or more, 0.6 second or more*
DTC Type	Two drive cycles, MIL on

* : Case 1
** : Case 2

Enable Conditions

Condition	Minimum	Maximum
Engine coolant temperature [ECT SENSOR 1]	68 °F (20 °C)	–
12 volt battery voltage [BATTERY]	10.5 V	–
State of the engine	Running

[ ]: HDS Parameter

Malfunction Threshold

	Case 1 The heater current is 0.8 A or less for at least 4 seconds while the heater is activated, and the heater current is 0.8 A or more for at least 4 seconds while the heater is not activated.
	Case 2 The heater current is 15.2 A or more for at least 0.6 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) AFHT line open
	A/F sensor (sensor 1) AFHT line short to ground
	A/F sensor (sensor 1) power supply line open
	PGM-FI main relay 1 power supply line open
	A/F sensor (sensor 1) failure
	PCM internal circuit failure

Confirmation Procedure

Operating Condition

Start the engine. Hold the engine speed [ENGINE SPEED] at 3,000 rpm without load (CVT in P or N, M/T in neutral) until the radiator fan comes on, then let it idle.

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.