General Motors P0008 on-board diagnostic code
“P0008 is a generic OBD-II code indicating an issue with the engine control module (ECM) detecting a variation in the mechanical timing between the crankshaft and bank 1 camshaft. The ECM uses sensors to detect the position of the crankshaft and camshaft(s). From these sensor signals, the ECM controls ignition and fuel timing under various speeds and loads. The code will illuminate the Check Engine Light and possibly reduce engine performance”.
Per research, there are a variety of things that could potentially set a P0008 code, including but not limited to, poor oil circulation i.e. clogged/inferior quality oil filter, low oil level i.e. oil starvation, sludge accumulation, crankshaft reluctor ring movement, and the proverbial stretched timing chain(s). Would like to suggest diagnostic and troubleshooting before ascribing a P0008 code to stretched timing chains as replacement may or may not be warranted. General Motors has at least twice re-designed the timing chains on the LY7 and can only find speculation as to why and which changes were made. Unfortunately, two of its biggest problems were overlooked, the oil life monitoring system and narrow oil cavities within the engine. The oil life monitoring system takes into consideration the condition of the oil, but not the oil filter. Moreover, General Motors issued a recall to re-calibrate the oil life monitoring system partially since many consumers were going too long between oil changes. Once upon a time, relied on the accuracy of the oil life monitoring system and changed the oil with +/- 20 percent of its useful life left. Upon further examination, noticed the oil filter had collapsed inward i.e. exceeded its filtering capacity. Therefore, decided to shorten the oil change interval since new oil and a filter are inexpensive in comparison to major engine repair work. The narrow oil passages make it more difficult for the oil pump to consistently circulate the proper amount of motor oil to lubricate vital engine components. In short, don’t depend on the oil life monitoring system to indicate a need to change the oil and always ensure the oil level is kept at the full mark on the dipstick.
Around 75,000 miles the check engine light illuminated, and a quick scan revealed the dreaded P0008 code. The light remained on for a few months before the vehicle was taken to the dealership. This was due to the fact it exhibited no signs of hesitation nor power loss. Meanwhile, the oil and filter were changed to avoid General Motors ascribing the code to an improperly maintained engine. Ironically, the service advisor checked the oil level while standing in the service bay before declaring “well the oil looks clean”. By the way, there is a bulletin regarding the stretched timing chain phenomenon 12-06-01-009d which used to do the warranty repair work. Eventually got the car back and was mostly satisfied with the outcome except an obvious oil leak around the oil filter cap housing. A quick glance at the receipt revealed General Motors only replaced the three timing chains, tensioners, thrust washers and a few gaskets, but not the chain guides. According to the service advisor, “the guides are not considered wear items”… comment withheld. Approximately 25,000 miles later, the check engine light began flickering on and off. This continued for a few weeks and noticed it would go away after accelerating and return shortly after idling. Reluctantly, took the car back to the dealership where it was concluded the timing chains needed to be replaced yet again. Said, timing chains should last nearly the lifetime of the vehicle, so why in a little over 100,000 miles would a car need a third set of timing chains?... crickets. Before leaving, the service advisor graciously presented an estimate of repair to the tune of around $2,000 which included replacing the water pump, thermostat, and other things “while we’re in there”. Chuckled on the inside a bit before decided pass on the offer.
A little time passed and resolved to either replace the timing chains, guides, tensioners, thrust washers, etc. with not tested [on the G8] aftermarket Cloyes parts or source an entirely new engine. Secured an estimate of repairs from a mechanic and he said, “maybe your computer just needs reprogramming”. Talked to the mobile programmer and he recommended taking it to a Master Tech with a $150 per hour diagnostic fee. Decided to throw $100 of parts at the problem in hopes of resolving it myself. Changed the oil and filter... P0008. Checked all visible wiring on both the camshaft sensors and variable valve timing solenoids. Changed all four camshaft sensors…P0008. Removed, cleaned and re-installed all four variable valve timing solenoids…P0008. At this point, was hoping for the proverbial “hail Mary” so revisited reprogramming the engine control module theory. Once again, spoke to the programmer and initially he declined to do the work stating it was a waste of money. After consulting with a Master Tech became even more adamant and persistent regarding not reprogramming the engine control module. Long story shorter, over 2,000 miles have passed and the P0008 code has yet to return (not even as a pending code). Apparently, reprogramming the engine control module allows for slight chain stretch as the initial parameters were too narrow. Maybe it’s a band-aid and only prolongs the inevitable… only time will tell.
In conclusion, a P0008 code may or may not require timing chain replacement depending on the severity of the problem. Bear in mind, every situation is slightly different and in both instances, the car ran fine outside the illumination of the check engine light. However, hesitation, sluggishness, torque or power loss are indicative of a larger issue and should be addressed immediately to avoid further engine damage. Hopefully, this thread sheds some light on the P0008 check engine code.
#NEVER GIVE UP
#AUDACITY OF HOPE
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