2003 BUICK RENDEZVOUS CXL CODE P1639 AND 5VOLT REFERENCE

Allen_7

Check engine light is on, code reads P1639 and 5 volt reference. Anyone familiar with the necessary repair to resolve the issue? Vehicle only has 62,000 miles. Thanks.

thecardoc3

The code means there is an issue with the 5v reference to the AC pressure transducer. It could be getting pulled low (grounded wire, shorted sensor) or pushed high (sneak circuit to power).

The best approach is to first measure the voltage on that circuit so that you can see what the ECM is seeing. If you don't have the ability to do that, you could try unplugging the transducer and clearing the code to see if it or what comes back.