: Problem after 99 STS Headbolt stripped and repaired

12-20-08, 04:16 PM
99 STS bought used 105,000 miles. After a couple thousand miles I found a headbolt stripped and the head gasket was leaking oil. Had this fixed but now it is using oil and the mileage dropped 5 mpg. Had the PCV valve replaced but it is still using oile and the mileage is not where it was before. (This may be due to the colder weather) Now it randomly stalls when in town and I lift my foot off the gas when coming to an intersection. It restarts on the second try and runs like nothing happened. The service engine light has not come on. Any thoughts about where to look? Thanks

12-20-08, 05:28 PM
Read the stickys at the top of this and Seville and Technical to learn how to pull your own DTC (Diagnostic Trouble Codes) from the DIC. Its all built in: you don't need an aftermarket scanner. There are several threads on how to interpret the codes, otherwise post them in this thread.

Read the entire Cadillac Technical Archive up in the black bar ^^^.

12-21-08, 11:17 AM
I did pull the following codes: B1983, B1344, B1652, B1760, P1599, P1617, U1064. The only ones that seem significant are: P1599 - Engine stall detected, P1617 Engine oil leve switch circuit and U1064 Loss of communication with DIM. I am not sure were to go with these. Any thoughts? Thanks

12-21-08, 11:40 AM
I posted up in Seville on your codes.......the only one of real concern is the P1599 stall code. The others could be transients......are the codes C - Current, or H - History ?? Codes will go to H after 3 successful start-run cycles, and automatically clear entirely after 40. Cold weather and hard starts set all sorts of voltage and communication codes. As I said above, establish a history and watch what codes come and go without clearing them for a while......see what the car is doing long-term instead of in a quick snapshot (If a serious code sets, the PCM will take a "snapshot" of the existing conditions, so the GM Tech-II scan tool ($4,000) can diagnose the problem.)

The oil level switch is on the front of the oil pan, next to the filter adapter. The connector may be loose or dirty, or the sending unit itself may be faulty. Easy fix during an oil change, otherwise use the good ol' dipstick.......the light should come on at 2 quarts low, not a panic situation as there's still 5.5 quarts in the engine.........if you need the sensor, call Luke at parts, Lindsay Cadillac, over there -------->

12-22-08, 12:20 AM
Thanks for your help.