Powertrain, generic · Fuel and air metering

P0135 O2 Sensor Heater Circuit Bank 1 Sensor 1

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

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.

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

Symptoms

  • Check engine light on
  • Longer cold-start phase without mixture control, more fuel and emissions
  • Follow-up codes P0133/P0134 possible (cold sensor)

Repair estimate

DifficultyEasyDIY possible
Parts and labour€5–300
Time0.2–1.5 h

Typical range across vehicles; the real cost depends on what the testing finds.

What to check first

  1. Check the heater fuse
  2. Measure heater resistance
  3. Inspect wiring

Parts involved

oxygen sensor heater bank1 sensor1oxygen sensor heater circuitfuses

Related codes

P0030P0031P0032P0053P0141P0155

References: law.cornell.edu, gsi.ext.gm.com, newtonnet.co.uk, saabwisonline.com.