Code 35 and Code 12
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Joined: Sep 2007
Posts: 253
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From: Charlotte/Wilmington, NC
Car: 1991 Z/28 1LE
Engine: 305 TPI
Transmission: 700R4
Axle/Gears: 3.42
Code 35 and Code 12
Hey guys. I'm currently driving a '91 RS with the 3.1 v6, about 151k miles. My service engine light is on, so I pulled the codes. I got 3 codes. A 15 (coolant temp sensor, which I know about/already fixed, it was just a stored code) a 12, which is no signal pulse to the ECM? and a Code 35, which is 'idle cannot be set to desired RPM.'
My question is, haha, wtf do those mean? More so, how, exactly would I go about fixing them?
I've done a basic search on here, with not too many results as far as explanations of the codes, however, I will continue to look, and if I find anything, I'll delete the thread. Until then, can anyone give me some help as to what exactly a Code 12 and Code 35 mean?
edit - got the code 12 figured out, I feel a bit ridiculous right now, haha. But still no luck on the 35.
edit number 2 - Alright, I got some more info on the code 35, which is apparently the IAC, but I'm not having any issues with idling or anything like that, and my TPS is almost new (maybe 2 or 3,000 miles.)
My question is, haha, wtf do those mean? More so, how, exactly would I go about fixing them?
I've done a basic search on here, with not too many results as far as explanations of the codes, however, I will continue to look, and if I find anything, I'll delete the thread. Until then, can anyone give me some help as to what exactly a Code 12 and Code 35 mean?
edit - got the code 12 figured out, I feel a bit ridiculous right now, haha. But still no luck on the 35.
edit number 2 - Alright, I got some more info on the code 35, which is apparently the IAC, but I'm not having any issues with idling or anything like that, and my TPS is almost new (maybe 2 or 3,000 miles.)
Last edited by tchernobog; Jan 14, 2009 at 01:28 AM.
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Joined: Sep 2008
Posts: 18
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From: San Diego
Car: 1991 Pontiac Firebird
Engine: 3.1L V6
Transmission: 700r4
Re: Code 35 and Code 12
Code 35 will show up when the closed throttle engine speed is 125 rpm above or below the desired (commanded) idle speed for 45 seconds. When I say desired or commanded idle speed I'm talking about the RPM level that the ECM is trying to achieve. For example, if the ECM wants your engine to idle at 800 rpm but something is causing your engine to idle at 925 rpm or higher, code 35 is going to pop up. Likewise, if the ECM is trying to set 800 rpm but it can't get it higher than 675, code 35 is going to show up again.
Since you don't have a low, unstable idle problem, it's most likely not the IAC that's causing Code 35 to pop up. First off, when did the code pop up? Is there a possibility that it occured shortly after you filled up your gas tank? The reason I ask is you could have some bad fuel in your tank which is causing the oxygen sensor to get pissed off, even though the O2 problem code isn't coming up. I would also check your PCV system for a vacuum leak and install a new PCV valve.
Glad to hear you got the Code 12 situation all cleared up, it's serious business
Since you don't have a low, unstable idle problem, it's most likely not the IAC that's causing Code 35 to pop up. First off, when did the code pop up? Is there a possibility that it occured shortly after you filled up your gas tank? The reason I ask is you could have some bad fuel in your tank which is causing the oxygen sensor to get pissed off, even though the O2 problem code isn't coming up. I would also check your PCV system for a vacuum leak and install a new PCV valve.
Glad to hear you got the Code 12 situation all cleared up, it's serious business
Last edited by Dakine858; Jan 14, 2009 at 03:40 PM.
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