OBD-II Trouble Code Description for P0431 Subaru

Warm Up Catalyst Efficiency Below Threshold

What does this mean?

OBD2 Code P0431 Subaru definition:
Basically this means that the oxygen sensor downstream of the catalytic converter on bank 2 is detecting that the converter is not working as efficiently as it should be (according to specs). It is part of the vehicle emissions system.

Symptoms

Possible sumptoms of OBD code P0431 Subaru
You will likely not notice any drivability problems, although there may be symptoms such as a rough/hard idle when cold.

Causes

Possible causes of OBD code P0431 Subaru
A code P0431 Subaru may mean that one or more of the following has happened: The catalytic converter is no longer functioning properly An oxygen sensor is not reading (functioning) properly There is an exhaust leak

Possible Solutions

Inspect for exhaust leaks. Next step is to measure the voltage at the oxygen sensor on Bank 2. In fact, it would be a good idea to test each oxygen O2 sensor while you’re at it. One thing to note is that many vehicle manufacturers offer a longer warranty on emissions-related parts. So if you have a newer car but it’s out of it’s bumper-to-bumper warranty, there still may be warranty on this type of problem. Many manufacturers give a five year, unlimited mileage warranty on these items. It’s worth checking into.

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