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1997 Deville 1999 Deville
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6 Posts
Discussion Starter #1
I took the 1999 deville in for its smog check (CA). When they plugged the car into the computer, the service engine light came on, along with traction control. Never seen either light lit on this car before. The actual emissions and visual inspection were fine, but the test failed because of the service engine light coming on. They say there is a P0606 code. Anyone else have this problem occur DURING the smog check? Hard to believe it randomly occurred at just the most inopportune moment-- anyone know if the smog check can CAUSE this failure? Any ideas for fixing, other than replacing the PCM?
 

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Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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69,870 Posts
First time I've heard this one, and I've done dozens and dozens of full scans of every sort of GM car possible.

Have the car scanned at a parts store and see what they come up with, then you do your own scan using the car's built-in scanner.

The "How to pull codes" sticky.
 

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Registered
1997 Deville 1999 Deville
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6 Posts
Discussion Starter #3
I pulled the codes through the onboard interface, and got the following:
P0603
P0606
B1350
U1255
C1278
B0533
U1128
U10106

I removed the P0603 and P0606 codes, and the service engine light is now out, and does not come back on from starting the car, or a short test drive. Not sure if it will reappear at the smog check station...
 

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Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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69,870 Posts
If a fault occurs in a monitored device or system it sets as Current and if it's an emissions fault it turns on the SES icon/light. If the fault self-clears it goes to History after 3 successful start-run-drive cycles. If the fault does not reappear after XX successful start-run-drive cycles it self-clears from History.

Always define your codes, and whether they're Current (C) or History (H) codes - it makes a difference.


 

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Registered
1997 Deville 1999 Deville
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6 Posts
Discussion Starter #5
All codes said "History." I cleared them all, took the car for a short drive, and none have reappeared, and the service engine light is out now. I suspect that there was some sort of flutter or short when the smog check station plugged in, causing the faults. I will try again with a different smog check station, and see if the problem recurs.
 

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White Diamond '03 DHS (with DTS floor shift)
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87,190 Posts
Be sure to drive it for a couple of days to complete the drive cycle to reset the "red flags" that tell them codes have just been cleared. Otherwise it is an automatic failure.

 

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1996 Fleetwood hearse
1996 Cadillac Fleetwood Superior Coach Hearse Conversion
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96 Posts
The P603 and P606 both go back to the PCM. One is a keep alive self test and the other a PCM self test. I'd bet when they plugged into your OBD port, they caused that error. I know some readers in Louisiana were not reading general motors vehicles correctly, failing many due to faulty hardware. This was causing many to not get a pass on emissions from the stations with the bad devices. That's been fixed but could be the issue there as well.
 
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