For the past 3 months, I have been experiencing a problem with my 2001 225 Coupe. I have had almost constant illumination of my check engine light. My first trip to the dealer to remedy this situation resulted in the diagnosis of a faulty secondary air injection valve. They replaced the valve, reset the computer and sent me on my way. About one week later, the check engine light came on again. I took the car back in and again the car was diagnosed with a faulty secondary air injection valve. They also noted that there was a vacuum leak in the system somewhere and they thought that the vacuum leak was causing the secondary air injection valve to stay open--thus causing the check engine light to come on and stay on. They had to order me another secondary air injection valve. The reset my computer and sent me on my way. Twenty-four hours and four cold starts later, the check engine light came back on.

As a side note, one of the service technicians at Park Place Audi @ Dallas, TX told me that the secondary air injection valve is activated during cold starts to deliver air into the engine and the emissions systems and if this part or any part fails its system check one or more times during four consecutive startups, the check engine light will come on and stay on.

Anyway, my third trip a week ago revealed a new clue. The diagnostic code that was in the engine computer pointed to a faulty secondary injection valve but they were puzzled by the loss of vacuum. They traced the loss of vacuum to the turbo pressure valve. This is NOT the bypass or diverter valve as we have all come to know and love. They replaced this valve and all appears well.

What was curious is that my car displayed no loss of performance during this whole dilemna?

Any constructive comments are welcome and appreciated.

 

also was traced to the "secondary injection" system.
They reset it once, the it came on again. They checked all the hoses claiming a vacuum leak and then... they replaced the DV and all is well. hmmm

Gene
225 TTR