Engine Light Won't Go Out



Hi - I have a 2003 VW Passat GL. Ever since it hit about 105,000 miles the check engine light won’t go off. The code that usually comes on is for oxygen sensors. I have had the sensors replaced time after time. The light has now been on for about 3,000 miles. VW said it is the temperature sensor and thermostat. My mechanic disagreed and replaced the thermostat sensor only. He replaced it for $375. The light is on again…day after repair. The car seems to run fine. Now I am trying to sell it but need that light to go off. Any suggestions?


What people would need to know to try to help you are the exact codes that have come out of the computer each time the light has been on. The light goes on - “diagnostic trouble code(s)” (DTC) is/are stored in the computer. The codes tell you about the system that you need to do diagnosis on. Codes cannot, for example, tell you to replace an oxygen sensor or a temp sensor - or anything else.

Check your invoices as they may have the codes recorded on them. For a current light you can go to major auto parts chains where you can often have them read for free.

The codes are in the format “P1234” - write that down exactly and post


Thanks. The dealer listed the codes on the estimate. My mechanic didn’t agree with the thermostat replacement code because I am still getting heat. He said this was just a dealer recommendation. I probably should have let the dealer do the work because they see this trick type of problem all the time. All cars seem to have the same issues at certain mileage points. If I could go to the dealer, spend $400 to get the problem fixed I would do it but can’t stand the idea of spending money on something that won’t work.


Right - so post the codes and people here can give you advice.


First, don’t pay for professional repairs unless you get a guarantee the recommended repairs will cure the problem…Mechanics must stand behind their convictions. Anyone can pull codes and replace parts. Professionals are supposed to KNOW what they are doing…You are paying them to make the light go out AND STAY OUT, not to go on a fishing expedition at your expense…

Having said that, should the bulb that illuminates the CEL burn out for some reason, who would notice that??

As a final note, you can buy a $25 cable and scan program (e-bay) for your laptop and pull your own codes and reset the CEL yourself, having fun and saving money at the same time…


should the bulb that illuminates the CEL burn out for some reason, who would notice that??

Maybe the owner when they discovered they did not know something was wrong before it caused some expensive damage.