Question about GMC Yukon XL
Time for oil change? Loose gas cap? Auto zone and several other parts stores will hook a reader to the plug under the steering column and read the code. Best news is they do it for free.
Posted on Feb 14, 2014
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Posted on Jan 02, 2017
SOURCE: Check engine and VSC lights on
I talked to you on the live chat, and I think that you may have missed the end of my typing...
What I went on to say is that more often than not, on the 02 4Runners, the Check and VSC lights in tandem look mainly after the emission system, and, since you stated no issues during the road test, I would guess that it is a fuel issue (too full/loose gas cap). But, if you can get the vehicle scanned, I will be very glad to provide you with more and better info if you provide me with the DTC codes. That would require your guy or an autozone hookup to a scan tool. I hope my clarification helps; and the graciouness of a FIxYa rating for this question would be greatly appreciated
Posted on Nov 06, 2008
The flashing is telling you that the engine is mis-firing, the dealer will run a test to determine the cylinder that is mis-firing, chances are it is something simple
Posted on Dec 01, 2008
So you have a P0421.
A code P0421 may mean that one or more of the following has happened:
As far as running conditions if it performs normally, you most likely need a catalytic converter. The good part of this is there shouldn't be any abnormal running conditions, so it should be fine unless the engine is running very rich for some reason. (it will usually smell badly when this happens) However, on rare occasions the cat can get hot and melt down causing an exhaust restriction..bad gas mileage, low power, and possible fire potential, but most likely this is not the case. (this is generally speaking here and covering all the bases... )
The most common thing with P0421 that the fuel injection computer detects that the cat is not performing to federal specs an need to be replaced. You will need to have it fixed before your vehicle inspection.
Good luck and I hoped this helped you.
Posted on Dec 27, 2008
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