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The fault codes will not clear on their own. You will either need to find someone with a Durametric Pro cable, take it to an independent shop that has the correct scan tool, or take it to the dealer to have it cleared.
Originally Posted by atlast911
Does anyone know if the CEL and fault codes can clear on their own or does they need to be reset?
Thanks. I bought the ecutool ($50 arrived from CN in 3 days) version and cleared them. I just wanted to make sure that was the right protocol.
Did anyone find a fix for this. Mine has been doing the same thing now for months. If I don't drive it for more than 2 days, I get a CEL. So only on cold starts. I take the negative from the battery to reset it. Also have new plugs and coils
Posting for a friend 2001 , 996tt all stock. No boost at WOT and only this codes.
If you baby the gas you are able to build boost, new MAF, new Plugs, No air leaks.
Help Please
My tech buddies tell me often with the Turbo when the intake hoses are installed a bit of rubber, a flap, gets rolled backwards as the hose is slipped onto the fitting.
The hose gets secured and there is no intake air leak under intake vacuum. There can be no leak under partial boost but as the boost goes up the thing leaks around the flap of rubber.
Another possibility is a hose is just bad, has a split or something. It doesn't leak under vacuum but under high enough boost it leaks.
Stand by for long winded explanation. I'm hoping something in the details might point to a solution.
I have a 2009 (997.2) Targa 4 with about 100k miles on it. I've only owned it 6 months (5k miles) and I don't know much about it's maintenance history. I think I'm 3rd owner. I only drive it on weekends.
A couple months ago I got a flashing CEL maybe 5 minutes (2 miles) after startup, as I was pulling into the gas station. After getting gas, I started it up (no cel) and drove 100 or so miles that day without seeing the code again. I had a very similar flashing CEL incident maybe a month ago. Went away quick and the rest of the drive was fine.
Just recently though, it got worse. I was due for a smog check. Only about a mile from my house and they took it strait in so the car was barely warm. Passed smog no problem, but 10 minutes later I got the flashing CEL again. It started running very rough, but I was a few miles from home so I continued. It never died, but idled horribly and I had to fight it to keep the RPMs up. Got better as I was going faster, but I'd say the issue was definitely still there....not just a cold idle problem.
I turned it off when I got home and read codes. P0300, P0304, P0305, P0306 (so one whole bank misfiring). I only have a cheap generic code reader. Reset the codes and started the car. Idled perfectly this time and flashing CEL gone. A few days later I drove it and had no problems. Then a couple days ago, I got the CEL and very rough running again. Turned car off and immediately back on. CEL gone and ran great.
I suspected cracked coils so I started with that today. I was hoping I'd find them a mess, but no luck. They look to be in great shape. Pulled spark plugs and they all look horrible to me, but I'm no expert. I'll go ahead and replace spark plugs since I went through the trouble of pulling the rear wheels and side mufflers to get to them. I guess I'll clean the MAF and add a fuel system cleaner next because it's easy, but I'm not holding out much hope that it'll fix the misfires.
Okay. Questions:
1. What are the chances a coil is bad if they're all visually in great shape?
2. Do the plugs look bad enough to have caused the problem? They all look the same so I'm guessing my issue wouldn't be isolated to just one side if plugs were to blame.
3. The car is getting older and has plenty of miles so I don't mind replacing a few aging parts with the hope of fixing this problem. What else should I check while I have the wheels and mufflers out? Considering age, what else may be to blame?
I've read about people changing everything from plugs, coils, MAF, Alternator, valves, AOS, ECU, etc. Has there been any consensus to date on the actual cause of this issue?
Probably unrelated, but just because a couple people have pointed to the Alternator, I also have a fairly rare, but intermittent issue with the stereo turning itself off and rebooting. Doesn't happen often and never in concert with the CEL, but thought it could be related to poor Alternator output. IDK?
What are the chances a coil is bad if they're all visually in great shape?
That can happen. I think thee is a test to measure its resistance to see if its bad. Just because it looks good, does not mean internally its not. Its cousins, Audis are notorious for this, they even had a recall to replace the coil packs on my B6 S4. All made by Beru.
Those plugs should not look that different from each other. They both look long past replacement time. Change all your plugs and coil packs.
That can happen. I think thee is a test to measure its resistance to see if its bad. Just because it looks good, does not mean internally its not. Its cousins, Audis are notorious for this, they even had a recall to replace the coil packs on my B6 S4. All made by Beru.
Those plugs should not look that different from each other. They both look long past replacement time. Change all your plugs and coil packs.
Thanks for the info. Changing plugs and testing coils this morning. I'll also throw in some fuel system cleaner and clean the MAF. I'm still thinking all cylinders in one bank misfiring intermittently must point to something more central to that bank vs individual coil/plug failure? I'm definitely no auto mechanic though. Just my logic.
Could a bad O2 sensor cause one bank to misfire? Isn't there one per? I'm assuming my issue is sensor or electric related because simply turning the engine off and immediately back on always eliminates the CEL and misfires, albeit temporarily.
Could a bad O2 sensor cause one bank to misfire? Isn't there one per? I'm assuming my issue is sensor or electric related because simply turning the engine off and immediately back on always eliminates the CEL and misfires, albeit temporarily.
When my coil (s) went bad on my 2000 Boxster S, the CEL light came on and the car shook. Shut it off, cooled it down, and it restarted and ran fine CEL off. Gets warm, bang. The newer 997.2 coils are different and supposedly much more robust and they are protected by the under pan so ..... never know.
I don't know what the codes were or how many coils went bad (at the same time?), as my indy just knew what the problem was given the symptoms. I don't remember how many miles I had on them..... maybe 150K or thereabouts so I replaced them all. He said IIRC all or most were cracked.
BTW: Those plugs look awful. I replaced the plugs twice now in 2009 C2S (40 and 80K miles) and they certainly didn't look like that.... and they all looked the same.
Each side has two Oxygen sensors. So you need four of them. Total cost from Pelican is about 800 dollars. At that age and miles, it would be a god idea to replace them. The cat on the side where they all misfired might be bad too.
At that these prices I don't really want to start shotgunning parts at it with the hope of getting lucky. It just passed smog while in the middle of having this intermittent issue. I'm guessing it wouldn't have passed with a bad 02 sensor, right?
It's a second car and winter is approaching so I definitely don't mind putting in a little work testing possible solutions myself. I may try swapping sensors from one bank to the other if it comes to that. I cleaned the MAF and added Tecron to the tank this morning. I know a lot of people say MAFs don't get dirty and this is a waste of time, but the cleaner is cheap and my air filters were beyond filthy so who knows. I also tested the coil packs with a multimeter. All read good as far as I could tell and they were almost exactly the same. Visually they look great too. May have even been changed before, but IDK.
New Plugs, Coils, Air filters should arrive Monday. To be honest, I'm already having buyer's remorse because I think the coils I have are fine. That's $250 I could have spent on shop labor if this problem turns out to be beyond me.
-Spark plugs looked horrible. Replaced them.
-Coil Packs looked great. Replaced them anyway.
-Air filters were filthy. Replaced them.
-Cleaned MAF.
-Found oil all over the engine side of the throttle body and oil inside the intake manifold. Not puddles, but a light coating all over (see pics). Cleaned what I could reach without removing intake manifold and completely cleaned throttle body.
Went for a test drive and initially the car ran better than ever. No misfires, smooth idle, quick response, lots of power. I attribute this to new plugs and a clean throttle body. Drove slow for a couple miles, then took it on the freeway for a couple miles (80mph-ish) and it ran great there too. A couple more miles in town to get back to the house. As soon as I parked in my driveway, I got the flashing CEL again, rough idle, obvious misfires. I didn't check the codes tonight because it was getting late, but I'm assuming it's going to be P0300, P0304, P0305, P0306 (one whole bank) misfiring again. I don't get any other codes, no MAF, no O2 sensors, nada.
I'm assuming my AOS is going bad or has a bad seal because there's oil in the intake manifold, but I'm not sure how that could cause this flashing CEL on only one bank. Any thoughts? I'm assuming the issue will be something specific to that bank. Also, this only happens after the car warms up and typically after I've been driving and come down off power. Any help would be appreciated.
just a few thoughts of my own recent $7000 experience with a slight hesitation and a check engine light. Had a spark plug lose the ceramic insulator and electrode into a cylinder, necessitating dropping the engine from our GT3, and replacing a piston and liner. When I felt the misfire, and saw my check engine light come on, I was a thousand miles from home, and immediately shut the engine down and coasted to the side of an Interstate. Took three flatbeds to get to a race Porsche race shop, where the technician found misfire codes on all cylinders, and ultimately found and fixed my car. A GT3 has a two stage fuel pump, and a prior service had failed to put one of the two fuses back in after cranking the engine to build oil pressure, so the car ran lean at WOT the first time I had the opportunity to make a long hard pull at WOT.
When my cylinder head was sent to a well known race engine builder, it was returned with the comments that all they needed to do was to polish the valves, and it was not necessary to trash the head, or even replace the valves. My car was down 6 weeks, and I had to fly out to bring it back when it was up an running again. The race shop told me I was lucky, because I had shut the engine off immediately, in several seconds, after the check engine light came on, and had avoided a far more expensive repair. GT3 motors run over $50K to replace. Mezger motors are very rebuildable, the other 911 motors are not.
So while my own expensive story is not really applicable to this thread's problems, I really do suggest that if your Porsche turns on the check engine light when you are out on the road, shut it down immediately, and have it flatbedded to someone who can fix it before it gets really really expensive.
CraigW1926. I am almost positive this is your issue. Below is a quote I posted on another thread.
Originally Posted by rombo60
Thread bump. This one is a GD little gremlin. Car would start fine and idle for about two minutes, but when it would go to low idle, misfires on cylinders 4, 5, 6. I knew plugs and coils would not fix the issue after reading multiple threads on this topic. I replaced them anyway and no luck. In my case, it ended up being the variocam solenoid on bank two. When the car would go to low idle on a cold start, it would create too lean of a mixture on bank two and misfire. Now she's purring like a kitten and I'm back to daily driving. Hope this might help others with similar issues.
The solenoid is only about $150-180. It's doable on your own or a good indie could do it in about 1-2 hours.
CraigW1926. I am almost positive this is your issue. Below is a quote I posted on another thread.
The solenoid is only about $150-180. It's doable on your own or a good indie could do it in about 1-2 hours.
Rombo60, Thanks for the reply. I saw your post last week as I was searching, but it just got lost in the sea of other possible culprits. I will give it a shot. If it turns out to be the fix, there's a case of beer coming at ya! These forums are a lifesaver for a guy like me. I can afford to buy the dreamcar, but can't afford to flatbed it to the dealor every time something goes wrong.
06-11-2014, 03:00 PM
