P0135: Lambdasonden-Heizkreis Fehlfunktion (Bank 1 Sensor 1)
Lambdasonden-Heizkreis Fehlfunktion (Bank 1 Sensor 1): Current draw or resistance of the upstream air/fuel ratio sensor heater element is out of specification.
| Trouble Code (DTC) | P0135 |
|---|---|
| Official SAE Definition | Lambdasonden-Heizkreis Fehlfunktion (Bank 1 Sensor 1) |
| Vehicle Subsystem | powertrain |
| Driving Severity | MEDIUM |
Observable Symptoms
- Check Engine Light on immediately after start
- Delayed closed-loop fuel control during warm-up
Most Probable Root Causes
- Open heater element inside Bank 1 Sensor 1 O2 sensor
- Blown O2 heater fuse
- Damaged sensor wiring touching hot exhaust manifold
Step-by-Step Diagnostic Procedure
- Check O2 heater supply fuse for +12 V with ignition on
- Measure heater pin resistance across O2 sensor connector (typically 2–14 Ω)