The emissions system is where the most expensive wrong guess in the trade gets made. A P0420 code names the catalytic converter, and a good share of the time the converter is fine and an upstream sensor, a misfire or an exhaust leak is what put the code there. Replacing the converter without checking costs a lot and fixes nothing.
Tested with the engine running before anything is condemned, and replaced properly when it has genuinely failed.
Upstream and downstream, checked live rather than swapped in pairs on a guess.
The small leak codes that usually turn out to be a gas cap, a cracked hose or a purge valve.
A leak before the sensor feeds it false air and produces codes that look like something far more expensive.
Maybe not. A converter code means the converter is not doing its job, and the most common reasons are an upstream sensor reading wrong, a misfire dumping fuel into it, or an exhaust leak ahead of the sensor. We check those before quoting the expensive part, because it is the single most over-sold repair on a car.
It is the most expensive part in the exhaust and it varies a lot by vehicle, so we quote after we have the car and confirmed it is actually the converter. What we will not do is quote one over the phone off a code you read at a parts counter.
Yes. We find why it failed, fix that, and make sure the readiness monitors have reset before you go back, which is the part people usually get caught out by after clearing a code.
Walk-ins welcome six days a week. The inspection is free whether or not you have the work done.
