Check engine flashed for 1 minute and then stopped

I have a 2002 VW Golf, with 203,000 miles on it. The check engine light is already on because the cat has worn out. I’m saving to buy a new one. However this morning about 5 minutes into my trip to work my check engine light flashed a few times. After pulling over and turning around to go back home the flashing stopped and the check engine light went back to be solid. Could the worn out cat have caused that? The car seems to run like normal. I did feel a little something when the light started blinking, but then it went away. The dealership and my regular VW mechanic have both said that the car is safe to drive regarding the catalytic converter until this winter when I get my tax return back. I have very little money right now for a repair. I should have more in a couple of months. The only thing that has caused the check engine light to blink in the past was the ignition coil pack. The car is on its third one and I know that feeling, this wasn’t it. Plus I just got a new coil pack in June 2014.

No, it could not have caused the flashing. Quite the reverse. The flashing suggests that you have severe misfiring going on. The severe misfiring may have caused your cat converter to fail.

I suggest you get this diagnosed ASAP. A flashing CEL is telling you that your engine is in danger of being destroyed.

I will take it to a big box place and find out what the codes are. The cat went out this summer with no misfire preceding it for more than a year, and that was the ignition coil. I had the car towed to the garage. I do have a sticky valve, but it was pretty quiet this morning, as it is most days, just once in a while I hear the lifter and when I do the engine idles a little rough.

That sticky valve just might be the root cause of your problems. But don’t consider this a diagnosis, that can and should be done “hands-on”. It’s only a random thought.

NOTE: that might have been the root cause of your previous misfiring problems too. You may not have needed all those coil packs.

It may have stuck too much this morning. It was really the coil packs in the other instances. The diagnostic tool showed that was the problem with the code, plus it was rainy both times. I’m still finding out if it gave a new code. In a couple of weeks I should have the funds for a small repair. I want to keep the car running to 300,000 if I can.

To keep the car running for 300,000 miles you need to fix problems when they occur. Continuing to drive an engine with problems creates additional, and often more serious, problems.

I know. I haven’t done too badly. The car is up to 203K. It may be a couple of weeks though. I find that many things on the VW cost under $500 to repair. That’s what I’m hoping.

You sound like you have a good head on your shoulders.
Sincere best.

I took it to have the codes read. Besides the one for the cat, it showed engine misfire cylinder 1. The guy at Advanced Auto said it very well could have been from the bad cat. Before driving over I took the car for a spin around town and there was no problem at all. If I scrimp and save I may have enough for the new cat for a Christmas present to myself.

What exactly were the codes, not what your mechanic interprets and certainly not what the salesman at Advanced Auto Parts told you. If you have a P0420 telling your mechanic that the cat is bad, it may not be the cat. Often this code is caused by the rear O2 sensor and it can also lead to an occasional misfire because it throws the A/F mix off. A bad exhaust manifold gasket or exhaust pipe gasket can also cause the code.

Write down the exact codes the code reader is displaying and post them here. Also look them up at this web site for a little more information, but do post them here as someone here may have had the exact same codes on your model VW and may have some insight as to the problem.

You may also want to look at a VW specific forum where you are more likely to run into experts (fanatics) on your particular model. We are mostly generalists here.

I don’t have the specific codes. I just saw the words engine misfire cylinder 1, which is probably better than all cylinders, I’d say. A few weeks ago I took the car in to the VW dealership and they confirmed the catalytic converter codes from their code reader. He said I could put this repair on the back burner to deal with at tax time this winter.

When I had the car out at lunch to take it to the big box place it ran just fine and it was raining too.

The cat converter won’t cause a cylinder one misfire, but a cylinder one misfire can cause a cat converter failure.

The cat converter canister contains a ceramic honeycomb coated with platinum-palladium. When hot, the platinum-palladium coating separates the oxygen atoms from the nitrogen atoms, NOx being one byproduct of combustion. That lowers the NOx count (in particles-per-million, or PPM), and also makes oxygen atoms available to the rest of the exhaust stream to convert CO (carbon monoxide) into CO2 (carbon dioxide) and even give unburned hydrocarbon molecules (gasoline) free oxygen to allow a “second burn”, which is the hydrogen and carbon separating and bonding to oxygen atoms.

The problem is that the NOx must physically contact the hot platinum-palladium coating for the process to happen. A misfiring cylinder can produce unburned fuel and carbon that can coat the cat converter plating, making contact with the plating by the NOx, impossible at the contaminated areas, rendering the cat converter less effective. At some point, the oxygen sensor “downstream” from the converter doesn’t detect a change in the exhaust from the “upstream” oxygen sensor and the “cat converter efficiency” code gets tripped.

Focus on fixing the misfire right now. Once that’s fixed, you won’t pollute the new cat converter when you get it and the job will be done. If you put the converter in with a cylinder still misfiring, you may damage the new converter. Since you’ve replaced the coil pack three times already, it might be time to try another shop.

When the CEL blinks, that almost always means a misfire has been detected. Misfires can damage the cat, but since your cat is already past its prime and needs replacement, and you have no other engine symptoms, I expect what happened is either you got some bad gas, with water in it maybe, or that sticking valve problem you had, it temporarily returned. Sometimes sticking valves can be addressed using fuel treatments. Have you tried any of those yet?

A misfire is what happens when the computer doesn’t detect the explosion that is supposed to happened when the fuel and gas in the cylinder gets compressed and ignited. Water in the gas will prevent ignition, and a sticking valve will prevent compression. It could be a spark problem too, like a bad coil pack, but when those fail they usually stay failed.

Suggest not to purchase a new cat until the sticking valve problem is better understood. Otherwise you may damage the new cat in short order.

Besides the one for the cat, it showed engine misfire cylinder 1. The guy at Advanced Auto said it very well could have been from the bad cat.
As a previous employee of AAP: don't rely on advice from AAP employees! During my year there, I encountered skill sets ranging from one older man who raced dirt track on the weekends (and could probably build a SBC blindfolded) new hires who needed to have the difference between SAE and metric explained to them. Without knowing "who's who," you can't know if the advice is any good.
He said I could put this repair on the back burner to deal with at tax time this winter.
The second you got the flashing code, that strategy went away. The CEL flashes *for a reason*: that reason being that you are in danger of CAT meltdown, and potential engine fire. They make it flash so that you damn sure don't miss it! You need to get on the cause of cyl 1 misfire ASAP; borrow the $$ if you don't have it--heck, sell your plasma if you have to! In the meantime, I'd recommend that you *put a test pipe in place of the CAT* until you figure the problem out. (Be advised that this advice is violation of Federal law--but Federal law ain't gonna do jack for you when you catch fire, now is it?)

**For all those sharpening their pens to fire back at me, consider that OP’s cat is probably already pretty non-functional after all the raw gas and overheating, so it’s not like this makes much difference from a pollution standpoint–just keeps him from burning up while he figures his problem out. Besides, I’m to understand that a car catching fire produces mass quantities of really nasty byproducts of combustion–my way avoids all that unpleasantness.

I ended up buying a 2012 Prius. I’m trying to sell the VW and I’m being very truthful about it’s problems, I’m also stressing the good things about it.

Lets consider another possibility. What if the cat is good and the issue is with one of the O2 sensors? The sensor is always in range, but its not doing its job, so the computer thinks the cat is bad. The sensor also allows the F/A mix to get far enough off that it can cause an occasional misfire.

I will offer that suggestion if I can get someone to look at the car to buy it. I want to sell it cheap enough that someone can put some money in it and make it run better.