2003 Passat Seconday Air Pump

My check engine light came on. I was a thousand miles from home. The diagnostic code said it was the secondary air pump. A new one was put on. I drove a thousand miles back to New England and the check engine light came on again. My mechanic here said it was the secondary air pump. He looked at the pump, asked if I had the one they took off which I didn’t. He said the pump looked fine, reset the system and the next day the light came on again. He said it was probably just a small vacuum leak and to continue driving the car. Now about 6000 miles later I’m beginning to wonder what affect if any this is having on the car. I don’t notice any change in the way it drives. Any suggestions?


Hey Dennis: I have posted a similar question with my 2003 Passat. My engine light comes on at times with no clear explanation from mechanics other than just replacing some expensive parts and crossing your fingers. I too am looking for help. Some mechanics tell me not to worry if the light doesn’t blink. I am thinking about just replacing the oxygen sensor, as I have heard this is common, and inexpensive, and may well be the problem. Any thoughts out there?

In addition to my 2003, I have a 98. The engine light on the 98 used to do what you describe and the dealer said the light probably was coming on as the result of not putting the gas cap on tight enough. I began to make sure that I always turned the gas cap to hear it make a continuous clicking sound and the problem went away. Who knows?

There’s more to the system than just the pump(although the pumps commonly fail). There’s some associated plumbing and a valve that has to work. Also, the feedback for the system is the oxygen sensor, that has to be ‘alive’ enough to sense the extra oxygen. Sound like you need a better mechanic.

Airheadearl, Thanks for the information. Are you saying a better mechanic would be able to isolate the problem or would they have to just start replacing things until the problem is resolved?

Go to a VW/Audi specialist independent mechanic. This problem is common on 1.8T(shared by Audi/VW) and an experienced mechanic will be on your side.

I don't know about air, but I would say a better mechanic would have checked to see what the real problem was first.  Error codes don't say that this or that is bad, they say the computer is getting a signal that this or that measurement is outside the expected norm.  It is up to the mechanic to figure out why.

You need a better mechanic. One more knowledgeable and who knows how to troubleshoot. Replacing parts is NOT the way to go. That’s like putting the mother before the baby carriage.
What does the secondary air (injection) pump do? It pumps air into the exhaust to lower emissions. It has no effect on engine performance.
You need to shop around for a mechanic, or shop, who knows their stuff on the air pump SYSTEM.

Thank you all. If anyone knows of a good mechanic on the South Shore of Massachusetts let me know.

I was wondering if you ever resolved this problem with the secondary air flow? I have exactly the same problem and have a good mechanic who has spent many hours trying to identify the issue only to have the light come back on. (I started with VW who told me nothing was wrong and then the light came back two weeks later - now it comes on after three days). I would ignore it but I need to get the car inspected in May…