The upstream oxygen sensor on bank 1 (sensor 1) has an electric heater so that it reaches its working temperature of about 300 °C soon after a cold start. The control module switches the heater on the ground side and checks driver voltage and heater current: GM fails it outside 0.3–2.5 A (or 3.1 A) and calls it 'heater performance', Ford outside roughly 0.22–0.465 A minimum to 3 A, Saab Trionic outside 0.5–2.3 A for 5 s. Manufacturers split heater faults differently between P0030–P0032, P0053 and P0135. With the heater dead, closed-loop control starts late after a cold start. If P0135 and P0141 appear together, check the shared fuse.
Medium severity. Can I keep driving?Yes, keep driving in moderation until it is repaired: the car usually runs fine once warm. On short, cold trips, you will use more fuel and produce more polluting emissions.
Bank 1 is the side of the engine with cylinder 1. Inline engines only have this bank. Sensor 1 is the oxygen sensor before the catalytic converter.
Symptoms
- Check engine light on
- Longer cold-start phase without mixture control, more fuel and emissions
- Follow-up codes P0133/P0134 possible (cold sensor)
Most likely causes
- Heater element of the sensor burnt out (sensor must be replaced)
- Fuse or relay of the heater supply faulty
- Heater wiring or connector open, corroded or shorted
- Unsuitable replacement sensor (different heater resistance)
- Heater driver in the control module faulty
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: easy
- It affects emissions.
What each character of P0135 means
- P: Powertrain: engine and transmission
- 0: Generic code: same on every make
- 1: Air and fuel
- 35: Specific fault in that system
Frequently asked questions
Can I keep driving with code P0135?
Yes, keep driving in moderation until it is repaired: the car usually runs fine once warm. On short, cold trips, you will use more fuel and produce more polluting emissions.
What causes code P0135?
The most common causes are: heater element of the sensor burnt out (sensor must be replaced); fuse or relay of the heater supply faulty; heater wiring or connector open, corroded or shorted.
Related codes
- P0030HO2S Heater Control Circuit (Bank 1 Sensor 1)
- P0031HO2S Heater Control Circuit Low (Bank 1 Sensor 1)
- P0032HO2S Heater Control Circuit High (Bank 1 Sensor 1)
- P0053HO2S Heater Resistance Bank 1 Sensor 1
- P0141O2 Sensor Heater Circuit Bank 1 Sensor 2
- P0155O2 Sensor Heater Circuit Bank 2 Sensor 1
Sources
- law.cornell.edu: 13 CCR 1968.2
- gsi.ext.gm.com: 18OBDG03A Engine Diagnostics
- newtonnet.co.uk: fordobd2012
- saabwisonline.com: dtc p0030 p0036 p0050 p0053 p0054 p0056 p0059 p006
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.