P0135 Code: Meaning, Symptoms, Causes & Fixes
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Causes ranked by likelihood
| Cause | Likelihood | DIY difficulty |
|---|---|---|
| Failed O2 sensor heater element — Replace the upstream sensor on Bank 1. | Most likely | 2/5 |
| Blown O2 sensor fuse — Check fuse before replacing sensor. | Possible | 2/5 |
| Wiring harness damage — Look for melted wires near the exhaust. | Less likely | 2/5 |
Symptoms of P0135
- CEL
- Slow oxygen sensor response
- Reduced MPG
How to diagnose P0135
- Confirm the code. Read P0135 with an OBD-II scanner and note the freeze-frame data (speed, temperature, load) recorded when it set.
- Check for companion codes. Look for other stored or pending codes such as P0141, P0155 — they often point to one shared root cause.
- Check: Blown O2 sensor fuse. Check fuse before replacing sensor.
- Check: Wiring harness damage. Look for melted wires near the exhaust.
- Check: Failed O2 sensor heater element. Replace the upstream sensor on Bank 1.
- Clear and verify. After the repair, clear the code and complete a full drive cycle to confirm P0135 does not return.
Can I drive with P0135?
Yes, but you'll see worse fuel economy until fixed.
Related codes
Related symptoms
Frequently asked questions
What does P0135 mean?
P0135 means o2 sensor heater circuit malfunction (bank 1, sensor 1). P0135 means the heater circuit inside your upstream oxygen sensor on Bank 1 has failed. The fix is almost always replacing the O2 sensor itself.
Can I drive with code P0135?
Yes, but you'll see worse fuel economy until fixed.
What is the most common cause of P0135?
Failed O2 sensor heater element — Replace the upstream sensor on Bank 1.
What are the symptoms of P0135?
CEL, Slow oxygen sensor response, Reduced MPG.
How much does it cost to fix P0135?
A typical shop repair range is $150–$500, depending on which cause it turns out to be. Cheaper causes such as wiring harness damage should be ruled out first.