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Q: I have a check engine light on

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My code is 0172, "right bank rich". I've change both O2 sensors, cleaned the MAF, installed new plugs and air filter, sprayed carb cleaner around the intake boots looking for a vacuum leak and found nothing. I don't suspect a hidden vacuum leak because this car idles smoother than anything else I own! Any suggestions? or keep looking for a vacuum leak?

My car has 210000 miles.
My car has an automatic transmission.

A P0172 rich code does not describe the items you have replaced. I would inspect the fuel pressure regulator for any signs of fuel in the vacuum line. Otherwise you may have clogged catalytic converters. You should feel a steady flow from the tailpipe at 3k RPM from about 4 feet away.

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