OBD codes / P0135
P0135
ModerateO2 Sensor Heater Circuit (Bank 1, Sensor 1)
P0135 is safe to drive with — it mainly affects warm-up fueling and emissions, not whether the car runs. Fix it at your convenience, but note it will fail an emissions test. Check the fuse and wiring before buying a sensor, just in case.
What this code means
Oxygen sensors only work once they're hot, so each has a built-in heater that warms it up quickly after a cold start. P0135 means the heater circuit in the upstream sensor (Bank 1, Sensor 1) isn't drawing the right current. Almost always it's the sensor's own heater element that has failed, so replacing the sensor is the usual fix — but a blown fuse or a wiring/connector fault can cause it too. Until the sensor heats up, fueling runs on estimates, which slightly hurts economy and emissions.
Symptoms you might notice
- Check-engine light, often with no drivability change
- Slightly worse fuel economy, especially on short trips
- Possible failed emissions test
What it costs to fix
Typical range: $150–$450 · about ~0.3–1 hrs of labor
| If the cause is… | Part | Labor |
|---|---|---|
| Upstream oxygen (O2) sensor | $50–$250 | ~0.3–1 hrs |
| Fuse | $1–$10 | ~0.1–0.3 hrs |
| Wiring / connector repair | $10–$120 | ~0.5–1.5 hrs |
The sensor is the usual fix and is a low-hundreds job. Always check the cheap things first — a blown fuse or a chafed wire is occasionally the cause and costs almost nothing. OEM sensors on some makes cost more than aftermarket.
The price swings on which cause it turns out to be — so confirm the cause before paying. Diagnose P0135 for my exact vehicle →
Frequently asked
Can I drive with P0135?
Yes — it's a low-urgency code that mostly affects emissions and warm-up fuel economy. The car will run normally; just plan to fix it, especially before an emissions test.
Does P0135 mean I need a new O2 sensor?
Usually — a failed internal heater element is the most common cause, and it's part of the sensor, so the sensor gets replaced. But check the fuse and wiring first; occasionally one of those is the cheap culprit.
What's the difference between P0135 and P0131?
P0135 is the sensor's heater circuit; P0131 is the sensor's oxygen-reading signal (stuck low). Different parts of the same sensor — and both can sometimes be fixed by replacing the sensor, but they're diagnosed differently.
How much does it cost to fix P0135?
Typically a low-hundreds repair if it's the sensor. Less if it turns out to be a fuse or a wiring fix. A seized or hard-to-reach sensor adds labor.
Seeing P0135 on your car? Get a diagnosis specific to your exact year, make and model.
Diagnose P0135 for my vehicleGeneric OBD-II reference. Manufacturer-specific behavior varies — confirm with a scan tool and, for safety-related codes, a professional inspection.