2001 GTP Flashing Service Engine Soon Light


zepol
12-03-2009, 06:56 PM
My service engine soon like came on about 4 days ago and I have been so busy that I haven't had a chance to find out what's going on. Today it started flashing and my wife said that she felt the engine shaking? I wasnt in the car so I dont know how accurate she was in her belief that the engine was shaking or not but I do know from past experience that she isnt very accurate in explaining an issue. LOL. Just wondering what the first steps I should take shoule be. Help!

GTP Dad
12-03-2009, 07:20 PM
You should have the computer scanned but this sounds like you have an engine misfire. The light will blink during a misfire and if it is bad enough the engine will act like she indicated. Once you get it scanned post the code or codes and we will help you with further advise. If it is random misfires you may need new plugs, wires, coils or a combination of all three.

tblake
12-04-2009, 02:21 AM
If multiple missfires are detected, I'd add a fuel pump, ICM, or cat converter to the list of possible issues.

If the light is blinking constantly while driving, do not drive it unless absolutly necessicary or you could cause further damage to the cat converter.

richtazz
12-04-2009, 11:01 AM
being an 01, the converter is the #1 suspect. GM extended the converter warranty on 01-02 Grand Prixs to 7 years/120k miles because of a known issue with the converters breaking apart internally and blocking the exhaust system. Your symptoms are consistant with this problem.

CrazyHorst
12-05-2009, 09:11 PM
The flashing SES light is the "engine damage probable" malfunction.

Basically it indicates a gross misfire condition or severe spark knock that can't be "fixed" by the PCM making adjustments.

I had this on my GTP and attributed it to the following...one of the coil pack posts was badly rusted. I sanded it clean with emery cloth and applied a generous amount of silicone dielectric grease to the inside of the new boot (also installed new wires and plugs at the same time). No more problems to date.

zepol
05-13-2010, 08:07 PM
Hopefully you guys follow old threads....I am currently unemployed so I havn't had a chance to really do anything with this issue other than replace the coil packs because that was the cheapest thing to try.

I took the car to autozone after you guys answered to have them do their free code diagnostic in order to pull the codes (Cant even afford a diagnosis LOL) and they couldn't get a reading. However my car got hit while in a parking lot and I just got it repaired and the auto body dude had one of his guys check the codes out and he told me that my issue was with fuel injector #5. He added that he couldn't tell me exactly what was wrong with fuel injector #5 because he didn't have the mechanics run the codes because they would have charged me.

What do you guys think I should do? As an FYI I found what seems like a great deal on a new fuel injector on ebay Delphi OEM for 24 dollars including shipping. I got my tax refund so I have the money to do whatever I need to in order to fix this issue at this point. :-)

old_master
05-13-2010, 09:01 PM
Codes will not tell you an injector is bad. If he told you cylinder #5, the code was most likely P0305. That code indicates a misfire on #5 but it could be a plug, a wire, a coil, the injector, etc etc. Best to have it checked out before you go pouring money into it on a guess.

You can swap plugs and wires with cylinder #3 to see if the miss changes to cylinder #3, (P0303) that's a free thing you can do.

zepol
05-13-2010, 09:36 PM
Codes will not tell you an injector is bad. If he told you cylinder #5, the code was most likely P0305. That code indicates a misfire on #5 but it could be a plug, a wire, a coil, the injector, etc etc. Best to have it checked out before you go pouring money into it on a guess.

You can swap plugs and wires with cylinder #3 to see if the miss changes to cylinder #3, (P0303) that's a free thing you can do.

Makes sense. I will try to get clarification from the auto body guy at the dealership and go from there. Thanks Old Master!

tblake
05-14-2010, 04:23 PM
Codes will not tell you an injector is bad.

Are you sure about that? What about a P0267, or a P0268? (injector 3 circuit low/high continuity, respectivly)

Zepol, is there any way you would be able to get us the exact trouble code? Even if you have to take it back to autozone for a free diagnosis again?

old_master
05-14-2010, 06:03 PM
Are you sure about that? What about a P0267, or a P0268? (injector 3 circuit low/high continuity, respectivly)

You're correct in the fact that those DTC's refer to an injector circuit, but they do not tell you to replace the injector. Following the flow chart could reveal a problem in the circuit to the injector. My point was that DTC's do not instruct you to replace a certain part. They tell you what system or circuit to test.

tblake
05-15-2010, 11:32 AM
I agree. Which is why it is probably best for us to have the specific code. It is probably a P0303 though. Which if it is, my next step before spending any more money on the car would be to do a compression check since number 3 is the center piston. To the OP, have you been running premium fuel in your GTP?

zepol
05-15-2010, 12:50 PM
Just got back from Autozone. They got two codes P0205, and P0305. There was another code that they couldn't read and the machine just said manufacturers code or something like that. I took it to two different AZ's just to see what they would suggest. The first guy was 99% sure it was an injector the 2nd guy said try some lucas injector cleaner and disconnect the battery for a min or two to clear the codes and see if it comes up again. I really appreciate the help!

zepol
05-15-2010, 02:58 PM
I guess I should say I was just asking those guys to see what they thought but plan on actually doing what you guys suggest in the order that you suggest it. You have never led me wrong and I appreciate access to such great minds :)

tblake
05-15-2010, 08:30 PM
P0205 = Injector Circuit Malfunction Cylinder #5

P0305 = Cylinder #5 Missfire

I would first ohm check the injector for cylinder number 5. Look for around 12 ohms. If that looks good, with Key on engine off, measure for voltage at the fuel injector plug pink wire. One lead of the voltmeter to a good chassis ground, and the other lead to the pink wire at fuel injector 5 plug. If you have voltage at the pink wire, then check the black/white wire which the PCM controlls the ground circuit. If advance will rent out a noid light set, that would be the best bet, or else I have also used a test light in the injector plug. Then start the car to make sure the noid light or test light flashes. If so, replace the fuel injector.

old_master
05-15-2010, 09:00 PM
Spot on! Remember to connect the clip of the test light to battery positive when checking for pulse on the injector ground wire. Make sure you use a digital safe test light. Just a plain old light bulb runs the risk of toasting the injector driver in the ECM.

If the P0205 is the first DTC, the P0305 most likely will also show up. But if the P0305 is the first DTC, chances are the P0205 won't show up. That's the importance of knowing the order that the DTC's were retrieved.

zepol
05-16-2010, 02:59 PM
Thanks! I will keep you guys posted on how everything goes.

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