I know this subject has been discussed at great length many times before but ...... My 03 Passat 1.8T has a flashing CEL only on hard acceleration, when I stomp it to the floor to get on the highway ect... The CEL doesn't stay on so is the ecu storing a code that can be read by a auto parts stores OBDII scanner? From the reading I've done on PW it seems like it's a bad ignition coil. I bought the car 4 years ago and since then I've replaced every coil pack because of misfires diagnosed from a steady on CEL. I admit that I'm a cheap ass and bought the cheapest coils I could find. I'll be replacing all the coil packs with premium products and I'd like to know if anyone here has purchased Bosch ignition coils and how did they work out? I can get real deal VW coils from online VW dealers for a very reasonable price. Thanks for the help
I would stay away from auto parts store scanning. They usually will only point you in a somewhat general location as to what Might be causing the CEL to come on with Imports. You will be tossing $$$ at parts and might not even fix the issue.
I highly recommend buying a $10-25 cable off Ebay (409.1), download the free VCDS 'Lite' from Ross-Tech. Do not install any disc that might come with the cable. This will allow you to read the codes.
As for your issue? Cheap coil packs certainly aren't a good option at all. If you can get VW coils. Get them.
Scanning at autoparts stores is fine, just don't take the recommendations.
Doesn't sound like coils. They usually just flat out die, not gradually. Get the ebay cable for vcds or an elm327 bluetooth obd and download the torque app if you have a smart phone. With torque, you can scan and clear ecu codes, plus monitor a/f ratios, temp, boost pressure and MAF readings to help diagnose. Same with vcds and much more, but not exactly portable.
I will say that I've had the exact same problem as you before, and the issue was a coil pack. It wasn't completely dead, but when you put your foot down the engine would miss and the CEL would flash. Eventually it just came on and stayed on for good. Replaced the coil pack the codes pointed to and no problems since. The auto parts store scans should be able to tell you what code you're throwing (at least they always have for me before I got VCDS), which is all you really need to know. If it's some sort of misfire related code related to one cylinder in particular then you know what coil pack went bad, but since you said you have cheap coil packs installed I would get all new ones from VW.
i've had some coils that had a low rpm miss, but worked at 2k+ without misfiring. it was strange. my only thought was maybe it had such a close intermittent winding failure, or just a lump of carbon in the cylinder oke:
So if the CEL flashes because of misfires.....new VW coils is hopefully the answer, I ordered a Vag-Com cable yesterday...I'm not much of a computer person so it looks like something new to learn about....Thanks for the help.
If you get a disk with your cable Do No Use It!!! Many of them are outdated and come with viruses. Hopefully the cable will come with instructions as to downloading it then you download the free 'lite' version from Ross-tech. Make sure you read the instructions and follow them to a 'T'
Bought 4 rev D ignition coils and 4 NGK 6458 plugs. What a world of difference that made. No check engine codes and I can mash it to the floor with no blinking CEL.
I wonder if one of your original coils had a dirty or loose plug clamp.
Anyway, the Rev. D coils, which were part of a mandatory emissions recall in CA and presumably some other states, and the NGK plugs were the right thing to do.
These engines are very picky about plugs. Try the old coils out again if you still have them.
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