Help with codes

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2000 XC70:

If the car sits idle for a minute or two the car wants to stall out. That is, the RPMs drop a bit under 1k, seems like it's going to choke out, but then the RPMs jump back up over 1k. This seems to happen a fews times a minute, but only when the car is sitting idle. Seems the car is regulating itself.

The car can be cold (sit over night) and this still happens. Only when it sits idle for, I'd say, 30+ seconds, but every time.

Today, the check engine light kicked on and I got the following codes:

P0422
P1237
P0302


It seems to be the cat, or perhaps a fuel pump, maybe a rear O2 sensor? (Typically fuel pumps cut out when they are hot, if it is at fault)

I got a quote from the dealer for a cat - $1100 just for the cat! I can get the other stuff from IPD.

Does this seem the likely culprit? That's a hell of a lot of cash...


TIA!

[ecbsykes]

P0422 brings up cat converter and the P1237 looks like fuel pump. I'm pretty sure those two are pretty unrelated. However, if the fuel pump is failing, it would probably explain the third code, P0302 which is a cylinder misfire (cyl #2).

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I agree with your explanation, but it seems odd that both would go out at the same time without there being a relation between them.

A faulty rear O2 can cause the cat code, how about the fuel pump code?

It's also weird, but this is just an observation, that this happened as soon as soon as the car rolled over 97.5k miles; just in time for scheduled maintenance. :-)