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Old 02-07-2008, 09:24 PM   #1
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Default Chevrolet Impala - P0420

Just got that code coming back from school today... P0420... Pretty sure it'* the cat since it'* been ticking lately, but I've been reading about Vital'* TPS sensor and I wanted to check it before I replaced the cat... I assume I'm supposed to put a voltmeter on it, but what am I looking for?

Ugh... Here we go again
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Old 02-07-2008, 10:48 PM   #2
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P0420 - Catalyst System Low Efficiency



You live in OH...remove the code from the PCM....
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Old 02-08-2008, 05:24 PM   #3
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I got that same code about two months ago, hit a pothole and it went away. I've been kind of worried about ot lately but dont exactly know whats wrong, can anbody shed some light on hat needs to be replaced
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Old 02-08-2008, 06:01 PM   #4
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Quote:
Originally Posted by 01bonne
I got that same code about two months ago, hit a pothole and it went away. I've been kind of worried about ot lately but dont exactly know whats wrong, can anbody shed some light on hat needs to be replaced
That sounds like your O2 sensor wire touching a spark plug wire...


Just took a 250 mile trip, hasn't come on yet... Still thinking it'* the TPS sensor, but we'll see...
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Old 02-15-2008, 04:05 PM   #5
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Default Re: P0420

Quote:
Originally Posted by petraman
I assume I'm supposed to put a voltmeter on (the throttle position sensor), but what am I looking for?(voltage wise)
Bump
Just got the code again, want to make it go away for EVVVVVER
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Old 02-15-2008, 04:24 PM   #6
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Nothing to do with the TPS sensor. It is a cat only code. Could be the spark plug wire being too close to the O2 wires, but you will get the same code with either a bad cat, or even with a high flow cat as well. You can either replace it with a stock cat, get an O2 emulator or get a PT and tune out the code to get rid of it forever. Won't effect you performance. Just an emissions thing.
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Old 02-16-2008, 10:28 PM   #7
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Still, I'd like to know how to test my TPS... I'm probably just gonna get the code removed next weekend, since I'm getting a catted downpipe this summer...
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Old 02-16-2008, 10:36 PM   #8
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There is a way that you can test it by checking it'* resistance with an Ohm meter. I can't remeber what it is exactly though so I will let someone else pipe in. Seems like it was 5mv or .5mv......somthing.
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Old 02-19-2008, 06:52 PM   #9
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Wasn't my tps sensor... Damn, now I have no clue...
This is what'* happening with my car right now. My car shifts really oddly, and it'* been doing it ever since I owned my car (even with the new tranny...). Sometimes it shifts nice and crisp (what it'* supposed to do with the Intense PCM) and other times it shifts soft like it'* a stock PCM. Also, whenever I let off the throttle when I want to slow down, the RPMs like to flunctuate between 700-1500 rpm. Up and down up and down... Also, sometimes it seems VERY sluggish (could be due to the fact it needs a tune up, but I wanted to include that...) Any ideas?

Still getting that P0420.
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Old 02-20-2008, 12:12 AM   #10
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Trans issues are not my fortee'. Is it doing this under the alternating under the same throttle amount?? Because under light throttle conditions it will shift much softer and will shift harder and more crisp under heavy throttle. But is sounds like maybe it is just being random? Have you checked your fluid level, color and smell? Could be a tune up thing. Have you checked your plugs and wires. Like it was said before if you have a crappy plug wire in the rear touching or close to the O2 sensor you will get that code. Other wise you have to figure out if it is the cat, delete the code, or get an emulator.
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