troubleshooting auto engine noises
VW jetta 2000... troubleshooting code PO422?
There's a rattling noise from under the hood and a few days ago the check engine light came on. I went to get it checked by a computer at Auto Zone and they gave me a code...PO422...main catalyst efficiency for bank 1 is below threshold for the current engine operating conditions. What's all that mean? It must be fixed but I just want to know what it is so I don't get screwed at the mechanic.
The catalytic converter is not a computer component. But the Federal law requires that the car ALWAYS monitor all emissions related components, and alert the driver when the emissions potentially can rise to a level of one and a half times tha maximum acceptable level. The strategy used here is to put an oxygen sensor behind the catalytic converter. When the computer sees a rise in activity in the rear sensor, it ASSUMES that the cat has deteriorated to an unacceptable level .
My recommendation is that rather than just throwing money at the code, go to a REPUTABLE, licenses smog shop, or the dealer, and ask that the cat be tested, along with the rear sensor.
Unless your little car has experienced major engine damage in the past, it is most LIKELY that the sensor is at fault. It is the less expensive repair of the two possibilities, but check them both. Eliminate the cause, not the GUESSES cause.
Good Luck
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