OOPs, it's a 2005 Pontiac GTO

Maintenance/Repairs
1

Had to edit this after first posted and cigroller and davesmopar first responded. Error codes and part number(s) to follow.

My brother’s car. Check Engine LIght has been on for years now. Car began to shake violently, the Message Board said the computer was in “Safe Mode Reduced Power.” Mechanic cleaned the pigtail wires to the throttle body. Car runs fine, for now.

Mechanic suggested purchasing a new throttle body if the car acts up again, which the mechanic thinks is likely.

Parts are getting harder to find for this car.

Any suggestions on the brand and from whom to purchase?

2

I thought the 2004 GTO 5.7 LS1 was a cable operated throttle body, with a replaceable IAC and TPS, why is someone saying it needs replacing?? What was the code??

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Why would it need a new TB if it had a wiring issue??

Unless I am missing something here, I would run as fast as I could from that mechanic…

2005 was the 1st year for the drive by wire TB with a 5.7L or 6.0L

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What were the specific error codes? (As dave asked).

And what dave said.

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I suspect there was an electronic throttle control circuit fault, he cleaned the connector and erased the fault.

The throttle body has been discontinued from General Motors, O’Reily Auto Parts shows a Dorman throttle body assembly for $350. Doesn’t the repair shop know how to order auto parts or are you going to perform the repairs?

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5

Summit racing shows the same Dorman TB for $216 in stock w/free shipping…

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Any manufacuturer’s suggestions other then Dorman?

7

The shaking is sort of a puzzling symptom for a problematic throttle body. The usual symptom would be idle-rpm wandering. Maybe it was wandering to such a slow rpm the engine was about to stall, which I guess might cause a shaking sensation just before it stalled. Did it ever stall out on you at idle?

The problem with replacing the throttle body is that the new one may have the same or other problems. Probably best if you can keep the original one. Suggest to ask your mechanic to remove the throttle body and give it a thorough bench cleaning. If you want to replace something, replace the intake air boots. The pleats may have developed cracks and are leaking air. Good opportunity to replace the engine air filter as well.

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Pick one.

https://www.google.com/search?client=firefox-b-1-d&sca_esv=646f761d74bca458&q=2005+gto+throttle+body&udm=28&fbs=AEQNm0A-TSThzBStWy2iQzbzvM8E5ytGZgQarMcVdjSRMHEykcJD9grKaAt6lsozr0RMsdPHhxQXtcEAVeJDa6I6dkofU52z7Mip8qJfU5kGUYvfscmR9BN5Bd8Dm6kW7y7xum69G6_chHqeUT4fWuMYYzuVKoTwCnLNpnv61a---26G8jo9_tk4y7Du53V2lTrkduhRfmErh6HkTNS5Ct2ljVx55X0hmQ&sa=X&ved=2ahUKEwilgY2C7aSHAxV_l4kEHbxbD5sQtKgLegQIDRAB&biw=1366&bih=579&dpr=1

Tester

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GM Genuine Parts 217-3153, LS3 Throttle body that according to a few GTO owners is a direct replacement for the LS2 Throttle body with fewer problems.

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I finally found my brother’s email in my spam folder. Codes are in his third paragraph.

"My car is a 2005 Pontiac GTO. 6.0l, LS2, V8, 400hp, 400 lb torque, Fuel Injection, Automatic 4 SPD Electronic Trans (but internet search found problem with someone who had a stick), RWD. (Someone said parts for a LS3 version engine would work too.)

The problem that occurred once: car shaking upon start-up, computer says “Safe Mode” - “Reduced Power”.

The error code my mechanic got is P-2135, which corresponds to the TB part. He also got error codes P-2176 (not sure what that covers) and P-0042 (which is for the oil regulator and I had him replace it).

My mechanic says the GM part number for the TB is 194-200-34, but I could not find that number in my internet searches (unlike the error codes that I found).

I found two people on the internet with the same problem and they said they think it is one or more of 3 problems: (1) TB, (2) TB pigtail connector wiring, and (3) pedal sensor switch. My mechanic said (3) is fine, so I think the problem is (1) and/or (2). Mechanic cleaned wires and connection and I had no error code on Thursday. I will drive it tomorrow to see what happens.

Internet said AC Delco, GM approved, part number 12570790 is the right TB part, but multiple websites say 'Not Available’.

Amazon, Rock Auto, Summit, and other websites carry multiple TB parts, but I cannot be sure if the part would fit my engine, and even if it does, whether the part maker is reputable. Prices are all over the place from $110 (Rock Auto) to $1,200, most prices from $300-$600. The $100 Rock Auto TB part says it will fit my car, but I don’t really know if it really will.

If I find the right TB part, I guess I might also might need some auxiliary parts - Fuel Injection (FI) TB seal?, FI Rail Bolt?, FI Rail Stop? FI + Insulator Retainer Kit?, FI O-Ring Kit?, Fuel Pressure Relief Valve Cap?, Multi-Port FI Kit? Rail? Bracket? The good news is that all these auxiliary parts seem available on AC Delco GM Part webpage"

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Why are you making decisions for your brothers car when you don’t know anything about cars?? Let the mechanic do what he does, his job with his warranty?? If you don’t trust his mechanic, then find one with a good reputation…

The induction system is a dry intake system, meaning no fuel goes through the TB or the Intake manifold (for the most part), so unless he has a fuel leak why are you asking about the fuel rail?? The TB bolts to one end of the intake manifold with 4 bolts, you may need a gasket or O-ring for the TB to the intake manifold if it doesn’t come with one, but you shouldn’t have to touch any part of the fuel rail system…

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Here’s the forum threads i’ve been looking at. With posters who’ve used the LS3 Throttle Body as a replacement with no issues. Most of the aftermarket ones are for the 2005 with a cable throttle not drive by wire.

2005 GTO Throttle Body | Pontiac GTO Forum

Dreaded Safe Mode | LS1GTO Forums

LS2 Throttle Body? | LS1GTO Forums