P0135: O2 sensor heater circuit malfunction (bank 1) sensor 1
The heater in an oxygen sensor isn’t working. The sensor needs heat to work, so after a cold start it takes longer to start reading and emissions are higher.
Updated
What P0135 means
An oxygen sensor only works when it’s hot. A heater built into the sensor brings it up to temperature soon after a cold start, so the engine computer can use its reading early.
The computer checks the heater circuit. P0135 means the heater of bank 1, sensor 1 (the one in front of the catalytic converter) isn’t working as it should.
P0141, P0155, P0161 and the heater control codes: the other heater codes
Sensor 1 sits in front of the catalytic converter, sensor 2 behind it, and some cars have a sensor 3 further down. P0141 is the heater of bank 1, sensor 2; P0155 and P0161 are sensors 1 and 2 on bank 2 of a V or flat engine; P0147 and P0167 are the sensor 3 heaters. The causes and advice are the same. For sensor 2 the fuel mixture isn’t affected much; the catalytic converter test is. Several heater codes at once point to a fuse or wiring they share, rather than to every sensor.
Many cars use the heater control codes instead: P0030 to P0032, P0036 to P0038, P0042 to P0044, P0050 to P0052, P0056 to P0058 and P0062 to P0064 name the heater circuit of each sensor, with “low” and “high” usually meaning it is shorted to earth or to a voltage. P0053 to P0055 and P0059 to P0061 mean the heater’s resistance is outside the expected range, which on some cars can also be a fault in the engine computer. The other codes between P0030 and P0064 concern other systems, such as turbo boost control.
P0141: O2 sensor heater circuit malfunction (bank 1) sensor 2
P0155: O2 sensor heater circuit malfunction (bank 2) sensor 1
P0161: O2 sensor heater circuit malfunction (bank 2) sensor 2
P0147: O2 Sensor Heater Circuit Bank 1 Sensor 3
P0167: O2 Sensor Heater Circuit Bank 2 Sensor 3
P0030: HO2S heater control circuit (bank 1 sensor 1)
P0031: HO2S Heater Control Circuit Low (Bank 1 Sensor 1)
P0032: HO2S Heater Control Circuit High (Bank 1 Sensor 1)
P0036: HO2S heater control circuit (bank 1 sensor 2)
P0037: HO2S Heater Control Circuit Low (Bank 1 Sensor 2)
P0038: HO2S Heater Control Circuit High (Bank 1 Sensor 2)
P0042: HO2S Heater Control Circuit (Bank 1 Sensor 3)
P0043: HO2S Heater Control Circuit Low (Bank 1 Sensor 3)
P0044: HO2S Heater Control Circuit High (Bank 1 Sensor 3)
P0050: HO2S Heater Control Circuit (Bank 2 Sensor 1)
P0051: HO2S Heater Control Circuit Low (Bank 2 Sensor 1)
P0052: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0056: HO2S Heater Control Circuit (Bank 2 Sensor 2)
P0057: HO2S Heater Control Circuit Low (Bank 2 Sensor 2)
P0058: HO2S Heater Control Circuit High (Bank 2 Sensor 2)
P0062: HO2S Heater Control Circuit (Bank 2 Sensor 3)
P0063: HO2S Heater Control Circuit Low (Bank 2 Sensor 3)
P0064: HO2S Heater Control Circuit High (Bank 2 Sensor 3)
P0053: HO2S Heater Resistance Bank 1 Sensor 1
The resistance of an oxygen sensor’s heater is outside the range the engine computer expects, so the heater may not warm the sensor as it should. After a cold start the sensor takes longer to start reading and emissions are higher.
Common causes: faulty heater in the oxygen sensor, wiring or connector fault, fault in the engine computer (rare).
P0054: HO2S Heater Resistance Bank 1 Sensor 2
The resistance of an oxygen sensor’s heater is outside the range the engine computer expects, so the heater may not warm the sensor as it should. After a cold start the sensor takes longer to start reading and emissions are higher.
Common causes: faulty heater in the oxygen sensor, wiring or connector fault, fault in the engine computer (rare).
P0055: HO2S Heater Resistance Bank 1 Sensor 3
The resistance of an oxygen sensor’s heater is outside the range the engine computer expects, so the heater may not warm the sensor as it should. After a cold start the sensor takes longer to start reading and emissions are higher.
Common causes: faulty heater in the oxygen sensor, wiring or connector fault, fault in the engine computer (rare).
P0059: HO2S Heater Resistance Bank 2 Sensor 1
The resistance of an oxygen sensor’s heater is outside the range the engine computer expects, so the heater may not warm the sensor as it should. After a cold start the sensor takes longer to start reading and emissions are higher.
Common causes: faulty heater in the oxygen sensor, wiring or connector fault, fault in the engine computer (rare).
P0060: HO2S Heater Resistance Bank 2 Sensor 2
The resistance of an oxygen sensor’s heater is outside the range the engine computer expects, so the heater may not warm the sensor as it should. After a cold start the sensor takes longer to start reading and emissions are higher.
Common causes: faulty heater in the oxygen sensor, wiring or connector fault, fault in the engine computer (rare).
P0061: HO2S Heater Resistance Bank 2 Sensor 3
The resistance of an oxygen sensor’s heater is outside the range the engine computer expects, so the heater may not warm the sensor as it should. After a cold start the sensor takes longer to start reading and emissions are higher.
Common causes: faulty heater in the oxygen sensor, wiring or connector fault, fault in the engine computer (rare).
Can I keep driving?
Check soon
Probably OK to drive short-term, but have it checked soon. Fuel use or emissions may be worse.
General guidance based on the code alone, not on the car’s actual condition. If in doubt, stop and ask a mechanic.
The car drives normally, but until the sensor warms up by itself, the engine computer runs without its reading: fuel use and emissions are higher, mostly on short trips.
Symptoms
- Often just the check engine light.
- Higher fuel use on short trips.
- The Oxygen sensor heater self-test not complete under emissions readiness.
Common causes
- Burnt-out heater in the oxygen sensor. The most common cause. The heater is part of the sensor, so the sensor is replaced.
- Blown fuse for the heater circuit. Your handbook or the fuse box lid shows which fuse it is. A fuse that blows again points to a short circuit.
- Wiring or connector fault. Heat from the exhaust can damage the wiring and connector.
Typical fixes
- Check the fuse for the oxygen sensor heaters.
- Check the sensor’s connector and wiring for damage and corrosion.
- Have the heater’s resistance measured at the sensor, and compare it with the value in the service information for your car.
- Replace the sensor if its heater is open. Clear the code; the Oxygen sensor heater self-test shows when the car has re-tested it.
Questions
Can I drive with P0135?
Probably for a short time, but have it checked soon: the app’s advice is that fuel use or emissions may be worse.
Can I fix P0135 without replacing the sensor?
Only if the fault is a fuse or the wiring. The heater is built into the sensor, so a burnt-out heater means a new sensor.