Failed emissions - no communication to PCM?

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pmclaug6

Member
Emissions test failed for '05 BMW Z4 - tech said the system failed to communicate with the PCM. Said that maybe someone tuned the PCM previously?? Looking for your guys' thoughts. Does that seem likely? Is there a way to reset to PCM myself without having to take it to a BMW dealership? They suggested I take it to BMW to reset PCM to factory settings. Thanks!
 
I would try and take it to Autozone or Oreilley or some place that will read your codes for free. If they car read your codes, then you know your PCM is at least "alive."

I once had a Mercedes that would not talk to the emission control place's computer, but would talk to my obdii reader and the dealers reader. The dealer said I needed a new PCM. I figured out that the obd port has two 12v pins. Everyone else used one of the 2 pins but the emissions place used the other pin. I had the port replaced and everything worked from then on. I really could have disconnected the battery and used a pick to pull the pin out and saved a few hundred dollars, but u live and learn..
 
Might be worth having a look at your OBDII port for broken/bent pins. You could also check each pin with a multimeter. Get a cheap code reader (if you don't already have one) and see if you can connect.

I would think it's far more likely that the port is faulty.
 
Update - a buddy of mine plugged in his OBDII reader. no issues. took it to a different place and the test communicated but most tests were not complete. I had driven the car for over 100 miles but did some research on the "driving cycle" required for these vehicles. Attempted to perform that myself, took it back and it passed. Thanks to all for your feedback.
 
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