P0135

Q: What does OBD2 code P0135 mean?

P0135 means: O2 Sensor Heater Circuit Malfunction Bank 1 Sensor 1. The heater element inside the upstream O2 sensor has failed. The heater warms the sensor quickly at cold start.

O2 Sensor Heater Circuit Malfunction Bank 1 Sensor 1

The heater element inside the upstream O2 sensor has failed. The heater warms the sensor quickly at cold start.

SeverityMinor

CategoryEmissions

Est. Repair Cost$100–$300

Code TypePowertrain

DIY RepairYes

⚡ Common Causes

›Blown heater element in O2 sensor
›Open circuit in heater wiring
›Blown fuse
›Failed ECM heater driver

⚠️ Symptoms

›Longer warm-up time
›Slightly poor cold-start fuel economy
›Check engine light
›May cause rich condition when cold

✅ How to Fix — Step by Step

Step 1:Check O2 heater fuse
Step 2:Test heater circuit resistance (typically 3–30 ohms)
Step 3:Replace O2 sensor
Step 4:Check wiring to heater circuit

💡 Pro Tip: O2 heater faults often cause other O2 codes during cold start — fix this first.

Repair Cost Estimate

Full Repair Estimate

$100–$300

DIY Possible?

YES

Severity

Minor

Frequently Asked Questions

What does OBD2 code P0135 mean?+

P0135 stands for O2 Sensor Heater Circuit Malfunction Bank 1 Sensor 1. The heater element inside the upstream O2 sensor has failed. The heater warms the sensor quickly at cold start.

What causes code P0135?+

Blown heater element in O2 sensor; Open circuit in heater wiring; Blown fuse; Failed ECM heater driver

How do I fix code P0135?+

Check O2 heater fuse; Test heater circuit resistance (typically 3–30 ohms); Replace O2 sensor; Check wiring to heater circuit

How much does it cost to fix P0135?+

Estimated repair cost for P0135 is $100–$300.

Is P0135 DIY-friendly?+

Yes — P0135 is generally DIY-friendly with basic tools.