My code reader tells me that this car has a secondary low air and one other fault(I forget), but is a related event that has set off the service engine light. A bmw mechanic tells me this requires the replacement of the air pump/valve at a cost of $500 and another $300 to do the job. Should I be looking at any possible other causes? Car does run fine, however.
Your mechanics diagnosis is plausible but it can be hard to tell if the valve and pump have failed or just one or the other. The valve is separate from the pump and commonly fails first allowing the nasty exhaust gasses/condensation into the pump leading to its failure. Have you or your mechanic checked for other vacuum leaks around the engine? In the least I would replace the valve and see if the pump is still alive. I have replaced just the valve on one car and the pump was good enough (though noisy when running) to keep the system operating without setting another code. This is an emissions related code so the car should still run fine, it just may not pass a sniffer test. YMMV on all the above, your mechanic has probably seen a lot more of these issues than I ever will in my lifetime. Matt
