2001 VW Jetta Check Engine Light stays on

I have 2001 Wolfsberg Edition 4D jetta (gas) with 180,000 miles, manual transmission. The engine light has been on for years and years. Usually what I do is take it in for an oil change just before a smog. They re-set the codes. I drive it to my office and back and the light would stay off and I could smog it. Until recently. In April, I took the car in for an oil change. And when I picked it up, it ran terribly. It was lurching like crazy. I had to keep slip the clutch to drive it until it warmed up and the it would mostly start running OK. I took it back to my mechanic and he thought it was a timing belt. I had already changed the timing belt at 119,000 miles in Feb of 2008. It seemed odd to me that this procedure needed to be done again after 60,000 miles, but I went ahead and had it done. That did not fix the problem. Then the mechanic replaced the air mass meter. That didn’t work. Then he replaced the coils. That didn’t work. My mechanic has had the car for a month and can’t seem to figure out what to do. He keeps getting different error codes - codes that don’t seem to make sense to him. Now I have two big problems. First I’ve spent over $1,500 in repairs. The car is only worth $1,500. And, it needs to a smog (my registration date is June), but he can’t smog it because we can’t get the check engine light to stay off long enough. Has anyone ever had this problem?

Sure, many have had that problem. Some States offer a waiver for money spent, but the best way for people here to offer suggestions is to post the error codes.

Without knowing the code history I can’t even begin to guess at the problem.

Maybe I’m reading this wrong, but from the way it’s written I get the impression that you went for years and years with the CEL on and nothing was done about correcting any problems. The oil was changed and the codes cleared so as to pass inspection.

That fixes nothing and possible what was once a single comparatively minor problem snowballed into multiple problems. Apologies up front if I took this wrong.

Right off the bat I can tell that your Mechanic…isnt too sharp. He should be using Both the handheld OBDII diagnostic computer for the codes…and THEN he should also be using the VW/Audi Specific VAG-COM… Without the VAG-COM most mechanics will be guessing at the problem AT BEST…

You cannot take most OBDII diag codes at face value…they should be looked at like puzzle pieces and not to be taken literally. This is true on basically all vehicles. In the instance of VW/Audi however…a mechanic who knows what he is doing will ALWAYS use a VAG-COM to read the codes and issues in REAL TIME… This system is what the factory and dealerships use…and it is simply irreplaceable and a “Must Have” to be able to accurately work on and repair any Audi/VW product.

The cost of the VAG-COM system is more than reasonable and consists of a special OBDII plug and cable along with software that can be downloaded via the web. The money you will save on repairs with this cable cannot be overlooked…you will rarely replace anything by mistake. Its essential basically. Without it…you will be doing things like this “Mechanic” is doing… replacing good parts with new good parts with no change in the running condition…in other words…WASTING Money…

Your mechanic made a serious error in diagnosing your running condition and coming up with the timing belt as the culprit… Which is to say he believed that the rough running was stemming from an engine Timing issue… Thats a pretty serious statement…and one which could have been positively proved out before touching that belt. The belt replacement NOT remedying the issue tells me that he was absolutely incorrect in his guess… It was also a guess that could have been proved out prior to going anywhere near that belt. This guys diagnostic prowess so far receives a big FAT “F” from me, if I do say so myself.

The issue you are describing sounds very akin to your coil over plug ignition system having issues…I do believe that your vehicle was included in the coil replacement recall… Im not sure what exactly is causing your running issue but you seem to be describing an engine misfire …Again, this is easy to diagnose and prove out… Without the car in front of me I cannot help to diagnose this problem very far as I am only as accurate as the problem description. IMHO…I would seek a real mechanic


You say after it warmed up it ran OK. That leads me to believe that it’s a bad temp sensor.

I’ve had the temp sensor replaced

I can understand how you might make that assessment, ok4450. That said, when I first purchased the car, I had a heck of a time with the check engine light issue. I tried several times with a dealer in Santa Rosa, Prestige Motors, to fix the issue. Each time however, I’d pay a couple hundred $USD, drive away and the check engine light would come on again maybe 150 miles later. After about 3 or 4 attempts, the dealership stopped charging me and gave me a free loaner car while they were working on mine - and that lasted about 3 more times until I finally gave up because it was such a hassle. I had read that as long as the check engine light isn’t flashing - then it isn’t a ‘pull over and stop’ situation. So I just put the metaphorical piece of black tape over the check engine light (not really - I just ignored it). That’s been many, many years now and I’ve never had a problem.

What about the possibility of a vacuum leak somewhere? A vacuum leak could cause poor running when cold and which could smooth out when warmed up.

It’s a very simple matter to do this with a vacuum gauge and it only takes a minute. The gauge will not show you where any potential leak is but it will let you know immediately if there is one.
If a leak is present then it becomes a matter of pinching or blocking off various vacuum lines until the gauge shows the leak has vanished.

Not many mechanics seems to use this cheap, and invaluable IMO, tool very much anymore. A few seconds to plug it in somewhere, start the engine, and in seconds you know if there’s any issue.

I’m puzzled that turning off the check engine light works where you live in Calif. Usually the car’s computer will inform the smog tech that the light has recently been turned off, so you’ll be told to come back after some monitors have completed, which mean after the CEL is back on. If this works for you to get it to pass smog, use it. But it is sort of surprising it works. I’m wondering if that is some kind of clue, like maybe there’s no problem at all, except with the CEL itself. It passes smog ok, right? And runs fine (until the recent oil change)? What are the emissions levels printed on the smog receipt? You may have trouble passing smog with the engine running poorly; hopefully you have no smog test requirements in the immediate future.

Edit: As mentioned above, suggest to post the current diagnostic codes, that might provide a clue where to start going forward.

I thought the exact same thing George… once you reset or erase the codes all the monitors also get reset. You wont have an engine light but you also wont have a vehicle that is in the “Ready” state to be plugged in and smogged. So I am also quite surprised that this car passes the smog.

I would go thru this vehicles entire vacume system…the original plastic PCV hoses and tubes are very brittle and are well known to crack and cause the CEL to illuminate. Those hoses will also cause rough running . I hate the “single use” clamps and connectors that VW/Audi uses…they really really suck.

After going thru all those brittle hoses on the PCV system I would then look into those coil over plugs… Since the WERE recalled and will be replaced free by any VW dealership. Those coils fail if you look at them wrong…so that really should be square one… Super easy to diagnose and repair…