Figuring out why your Check Engine Light is on means deciphering OBD-II (or “OBD2”) codes, and that can be kind of annoying. That’s why Car Bibles did it for you! You’re welcome, now let’s get into solving your issue.

OBD2 P0135: What It Means

This code reads as O2 sensor heater circuit malfunction (bank 1 sensor 1).” That means that the internal heater in the O2 sensor has failed. It’s usually impossible to fix what’s going on internally, so when it’s broken, it’s really broken.

Likely Symptoms

Here’s what you may experience due to the P0135 code:

  • Check engine light.
  • Decreased fuel economy. The heater circuit does most of its work when the car is cold. It heats the O2 sensor so that it can obtain correct readings on how the engine is running.
  • Rough engine running. Usually this will manifest itself in cold starts, where the O2 sensor can’t read the exhaust correctly. Note: If the heater circuit has failed, usually the O2 sensor isn’t far behind.

Probable Causes

Here’s what could be causing the issue:

  • O2 sensor failure. The only issue this could be is a bad O2 sensor. 

What Part Is Potentially Affected?

Very rarely, this can cause engine damage. Usually, you can hurt your catalytic converter if you let the engine run poorly for long enough.

Possible Fixes

Here are the most common fixes to remedy the P0135 code:

  • Replace O2 sensor. The only fix to a bad O2 sensor heater is to replace the O2 sensor. Pretty straightforward!

Finding The Parts You Need

Now that you’ve figured out what’s wrong with your hooptie, let’s talk about where you’re gonna find that part’s replacement.

There are plenty of places you can buy auto parts from, but Car Bibles gets paid if you click this Advance Auto link so that’s the one we’re serving up. Advance Auto Parts also has delivery, curbside pickup, and a host of helpful diagrams to aid your repair!