I have a 2005 525 with a merc monitor connected. This weekend i got an alarm on the monitor with code 121. The engine ran ok to get back home, if I am reading the code table right this is a TPS sensor error. I have the info to check the sensor ie check the voltage output. Interested if I am on the right track or should I get a mechanic to connect to a diagnostic tool before I change the sensor. By the way is there a less expensive replacement for this sensor? I think Merc is asking $200+ for the sensor. Thanks for any help!!

525efi tps ? If yes, i believe AC Delco #17106682 is what you are looking for.

Yes that’s what I was looking for. Thank You!!