What Does the Engine Code P2A01 Mean?

A P2A01 engine code signals a problem with an oxygen sensor, related wiring, or your exhaust. A P2A01 error may cause your car to fail an emissions test.
Written by Rachel Rigolino
Reviewed by Melanie Reiff
A P2A01 code points to an issue with the O2 sensor circuit, specifically the rear heated oxygen sensor. The sensor helps your car’s central computer—the Powertrain Control Module (PCM)—to supply the engine with fuel and regulate your spark plug/ignition timing.
To determine why your
check engine light
is coming on, consider using an OBD-II code reader. This reader can help in diagnosing the problem, but keep in mind that you may want to seek out the help of an expert to identify the specific cause(s) of a P2A01 engine code.
Fortunately, the #1-rated
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has put together this guide for what a P2A01 code might mean, what to do about it, and how to fix your car so that you’ll pass your next emissions test. 
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What does the engine code P2A01 mean?

Definition: O2 Sensor Circuit Range/Performance Bank 1 Sensor 2
This code indicates a problem with your exhaust system. The O2 (oxygen) sensor associated with this code measures the amount of oxygen in your exhaust. It may be that the sensor is bad, or it may mean that your exhaust has a leak. Another cause of this error may be bad connectors or wiring to the sensor.

How much will it cost to fix?

It will typically take about an hour to diagnose this problem, and repair shops typically charge $75-150/hour
Once diagnosed, a common fix for a P2A01 code involves putting in a new oxygen sensor. Replacing an
oxygen sensor
professionally typically costs between $320-$380. 

What can cause the P2A01 engine code?

Some common causes include:
  • A bad sensor
  • Problems with wiring that connect to the sensor
  • Exhaust leaks
  • A powertrain control module (PCM) problem
MORE: How to know if a mechanic is taking too long with car repairs

Common symptoms of a P2A01 engine code

Drivers will likely notice the following symptoms:
  • Poor fuel economy
  • Problems with engine performance
  • Failed emissions test

How serious is a P2A01 code?

Problems with oxygen sensors may not seem to need your immediate attention, but a P2A01 code indicates an issue with exhaust gasses. Keep in mind that a faulty oxygen sensor will likely result in your vehicle failing its emissions test. If this is the case, you’ll need to replace the sensor before your car or truck can pass inspection. 
Address this code as soon as possible. You don’t want to fail an inspection and be forced to take your car off the road. Also, the code may signal a significant problem with your exhaust system.
MORE: How to pass emissions testing

Can I fix the P2A01 engine code myself?

Replacing a sensor professionally is relatively affordable, so it may be worth it to avoid the hassle and have your mechanic do it. However, you may be able to fix the problem yourself, assuming that the P2A01 code is being caused by a bad sensor (and not something more complex).
Replacing an oxygen sensor can be a fairly straightforward procedure. You’ll need at least 1 to 2 hours to do the job. 
  • Make sure your vehicle’s engine is cool. You will be working on the exhaust system, which can cause burns if it’s still hot.
  • If you need to get under the car, use jack stands to lift the vehicle on a level surface. Use wheel chocks to secure the car.
  • Locate the sensor and remove it. Refer to your vehicle’s manual to figure out where the sensor is located. You’ll need to disconnect the sensor from its wiring. 
  • Install the new sensor and plug it back into its electrical connection.
  • When you start your car, see whether you notice a difference in the engine. You may need to clear the check engine light manually.

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