"Check Engine" light on all the time on '96 911 Carrera

[ericross]

For some time now my "Check Engine" light has been on. Several months ago when I lived in San Francisco I had my mechanic check it extensively (I have only worked on my 914, and I had been too busy to check it out myself). He changed the spark plugs, plug wires, and a few other relatively minor things (I can get a complete list, but I don't have it here). His conclusion: he had no idea why the light was on, but he couldn't find a single thing wrong with the car. A friend of mine who races thought it might be a bad chip (I assume he meant DME).

If anyone has seen this problem before, I would greatly appreciate any insight -- it makes me nervous to drive it hard while this light is on. And I apologize if this was covered in a past posting, but I couldn't find any references to this problem.

Thanks for any help.

[Doug Zielke]

The DME will have a diagnostic port, that a dealer can download data from, possibly telling why the light is on. See your dealer.

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'81 SC Coupe (aka: "Blue Bomber")
Canada West Region PCA
The Blue Bomber's Website
"If it ain't broke...we'll help you fix it 'til it is!"

[This message has been edited by Doug Zielke (edited 09-25-2001).]

[cabman]

Those "check engine soon" or "service engine soon" or "check engine" lightbulbs are completely useless!! They just send you on a wild goose chase and I dont see the need for them on any car.

It's like that pointless electronic arrow that pops up to tell you when to shift on 1988 Carrera.

Shchit like that they add to modern cars these days take away from the raw feel that a "true" Porsche 911 should possess.

some car features are just completely useless and do more harm than good.

anyway, good luck searching for a possible phantom problem on your "porsche"

[Adam]

Cabman,

I think that's pretty cold. I agree about the service engine soon lights, but the legitimate OBD-Fault Code lights are not to be ignored. They're there to advise the driver and to avoid litigation if they're ignored. "Hey, we warned you, buddy!"

Personally, I'd like to know if any of the safety systems on my MODERN car were inoperative or malfunctioning. I'd love to know that the ABS wasn't working if I was driving a nice 993. Then I could adjust my driving style accordingly. I'd also be pleased to know if the motor wasn't running right, detonating too much or if any of the Electronic Injection was playing up.

It's a sure fire way to avoid spending big dollars on repairs. I've seen people ignore service intervals on modern cars (I work for a large Car Dealership) and have seen cars go for long periods, avoiding scheduled maintenance and suffering horrific faults like siezed cams/cranks and ruined injectors. They hope to save money by not servicing "when the stupid book says to" only to get indignant when they have to pay TWICE that amount in repairs.


Preventative maintenance is always cheaper in my book!

Ericross, I'd take it to the dealer. Only takes 5 minutes for the guys to hook up the diagnostic computer. Good Luck!

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Adam Chaplin
1976 911 2.7 Euro
My 911 Website
Pelican Gallery Page
Porsche Owners Gallery Page

[Wayne 962]

I think that he was referring to the type of EGR lights that turned on at 30,000 miles or so to have your CAT checked - not that there was actually anything wrong with the car.

These timed warning lights can be very confusing...

-Wayne

[john70t]

I've talked to guys working in many types of dealerships and I hear that even they have a hard time getting repair information for a lot of the new(and sometimes old) equipment.
Toyota seems to be pretty good as well as Ford but some of the German manufacturers haven't caught on to the idea of user-friendly (for whatever reason). When I buy my next car it's going to have in the passenger seat a brand new factory repair manual, and access to technical bulitins.

[Formerly Steve Wilkinson]

FYI, for all you people who like to be in control of your own lives, Baum Tool sells software for $395 that does virtually everything the dealer's $5,000 OBDII diagnostic computer does, and you simply install it on a Palm Pilot. Plug it into the diagnostic port of any post-'95 car and it reads out what fault code (and definition) is turning on your check-engien light, reads out all of the engine's operating parameters (rpm, temps, % power, etc.) and graphs and saves them, etc. etc. Also turns off the check-engine light if it's come on for a spurious reason. Or you can learn that it's on because of a faulty water-temp sensor or whatever and replace it for $30. I use it on my A4 Audi with great success, though my Porschie is an '83. Seems that you'd save the $395 in a dealer visit or two, and many of us have Palms.

Stephan

[ericross]

Thank you for the replies.

The mechanic I used in San Francisco (John Gardiner Automotive) ran the diagnostics -- code stated "misfire". To be safe (my recommendation), he replaced the spark plugs, two distributor caps and the spark plug wires. The mechanic couldn't find anything wrong with the car; it drives well and does not produce any unusual sounds or problems. He obviously checked the plugs to be sure all cylinders were firing properly, etc. and other more basic steps. He (and I) wouldn't know there was anything wrong with the car if the "Check Engine" light was not on. He was at a loss as to how to proceed from here -- he believes the car just needed to be driven harder than I was driving it. As background, they have done very good work in the past and saved me a great deal of money.

The big problem for me is I moved to NYC two months ago and am reluctant to pay someone to re-run the same course of action to date.

Any other suggestions as to why this light is staying on? I'd rather know I am not damaging the car before I really take it out to the track. I assume a possibility is the light switch is jammed open, but I'd want to know the engine is fine before I cut the switch out.

Thanks again for any suggestions.

[john walker's workshop]

a bosch hammer can usually delete the fault codes. if it deletes, and the light stays out, then it was a non-problem. if there's a DME problem it should show up on the tool.