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2008 STS
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I recently experienced the dreaded P0008 DTC on my 2008 STS 3.6L [email protected] 63,000 miles. I had the car scanned at three different locations as well as by my own scanner. In all cases, the scans returned P0008.

Unfortunately, my license plate renewal was due by May 31, 2015 and an emissions test was required. With this DTC showing, there was no way that I would pass emissions.

With internet searches, I found the SB referring to stretched timing chains and GM’s Special Coverage 11340. I called the national Cadillac Customer Service (1 800-458-8006) with my VIN#; and they confirmed my vehicle’s coverage under that policy. They had a nearby Cadillac dealership call me to make an appointment to have my STS repaired at their expense. The Cadillac telephone rep also confirmed the 120k/10 year warranty extension.

The necessary repairs were completed in 48 hours. When the STS was returned to me, I headed for the emissions test facility. The tech hooked up the computer and after five minutes he handed me a VEHICLE REJECTION NOTICE. He informed me that I had failed the emissions test due to lack of response from my STS. The form indicated that the Catalyst and Evap Systems were “NOT READY” and the tech wrote “Drive Cycle” on the rejection notice. I asked him what the problem was, and he told me to call Cadillac and sent me on my way. He was a real jerk! I made a number of calls including the dealership, but no one was able/willing to tell me exactly what constituted a “Drive Cycle.” Everybody had an opinion and even some anecdotal examples--but no definitive answer.

Back to the internet, and after a good deal of searching I found GM’s drive cycle which I will post below. The problem was that it was impossible to complete the drive cycle in a metropolitan environment. Most steps, especially 5 and 8 which require driving 55 mph for 3 and 5 minutes respectively. Then decelerate to 20 mph only by taking your foot off the accelerator and coasting. My STS took almost 5+ miles to get down to 20 mph! So, for me to complete the GM drive cycle, I needed a minimum of an 8 to 10 mile open unoccupied stretch of road! The Interstate or any other major thoroughfare was out because of the 20 mph requirement-an 80mph 18 wheeler up the exhaust pipe would sort of eliminate any need for an emissions test. I ended up driving up and down desert two lane “roads” all night until I had reached about 200 miles total. I was pulled over once by a deputy sheriff who suspected that I was DUI. I showed him a printout of the GM Drive cycle; and after a bit of calm conversation and explanation, he wished me “Good Luck” and was returning to his patrol car when he turned around and said that he knew of a much better location to complete the cycle and would be willing to keep in contact with me via cell phone to tell me if other vehicles were approaching. We went to the location he recommended and I went through the cycle twice. What a great guy!

The deceleration process appears to be the culprit in resetting the OBDII as most of the important diagnostics are performed during this procedure.

In Arizona (Tucson and Phoenix), you can fail (being NOT READY is a failure) and get checked the next day. If you fail then, you have to wait an additional 3 days, and if you fail then, you have to wait an additional 7 days to be retested. You have one free “get out of jail” card if you or your mechanic/dealership certify by signature that the vehicle is READY to be tested. If you use this “card” and your vehicle is still NOT READY, it will fail and 1,3,7 day waiting times are extended.

The second tech I got was a real pleasant person who seemed hell bent on helping me out. I was just about to take the STS back to the dealership to have them tell me whether or not I was READY. The pleasant ADEQ young lady, about leaped over the counter to tell me NOT to do that as it would negate all the driving I had done all night. According to her, the equipment used by the state is either “benign” or “passive” meaning (again according to the tech) their equipment does not transmit ANY query via electrical pulse to your vehicle--it only reads what the vehicle “voluntarily” transmits. All of the hand scanners including the ones used by the various auto parts stores DO send an electrical pulse which will cause another NOT READY status. According the her, because of the different types of equipment available (and the fact that so many people had tried to “hack” the OBDII), there is no way to know in advance whether or not your vehicle is READY for the test.

I showed (in fact gave) her a copy of the GM Drive cycle. She recommended that I have the STS tested right then and she wouldn’t count it as my one free test as I was in fact assisting ADEQ by updating the information they can give to vehicle owners in similar circumstances. I took her up on her offer and passed emissions testing. The results are immediately available to DMV, so I went on line in the ADEQ parking lot and renewed my plates for two more years.

I have no idea at what point during the night my STS became READY, and I don’t know if the inspection station techs can alter the results of the tests. However, there are huge signs all over the inspection station warning about the consequences of bribing, or attempting to bribe, the examiners, which leads me to believe that the test results can, in fact, be altered. Not my way of doing things, so it’s not really relevant to me

Anyway here is the GM Drive Cycle:

Semper Fi!
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