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Error Code P0008 is actually a generic term used to describe a problem in the Engine Position System Performance Bank 1 (refers to the engine with Cylinder #1). Usually a trouble associated with the engine’s mechanical timing.
The error code refers to a problem with the engine’s mechanical timing. The code appears in scanners to show issues on the vehicle’s ECM (Engine Control Module) as it detects variation on the engine’s mechanical timing from the crankshaft to the bank 1 camshaft.
The ECM uses its sensors to identify crankshaft and camshaft positions. Using these sensor signals, the ECM controls the vehicle’s ignition and fuel timing under various loads and speeds. When the code is detected, it triggers the Check Engine light and can possibly reduce the performance of the engine.
This code is most common among Buick, Suzuki, GM, Cadillac, and Holden makes. Also, GM actually even offers service bulletins for their vehicles for this code, which suggests replacement of the timing chains.
Aside from the illumination of the Check Engine light, you may notice drivability problems. Some of the most common symptoms of this error code include:
- Malfunction Indicator Lamp (MIL) or Check Engine Light on
- Decreased power
- Rough acceleration
- Poor fuel economy
- Engine Idle Quality
- Noise in Timing Chain
The main cause of this error code is stretched timing chains. Though this will not eliminate timing belt stretch, tolerance is looser on engines equipped with timing belt than on engines with timing chain.
It could also be a problem on the crankshaft reluctor wheel moving and no longer referenced to TDC (top dead center). Or a problem on the timing chain tensioner.
For GM makes, the problem is usually caused by the tensioner and sliders. This will require a re-calibration of the ECM which involves a series of long loosening tolerances. Experts believe this may be caused by infrequent oil changes and not using the recommended oil, or using a cheap oil filter which may accelerate chain stretch.
Though quite rare, this code may also be a case of jumped tooth, as the flexibility of timing belts make them more susceptible to cases of jumping teeth.
Other common causes include:
- Worn-out timing components such as gears, guides and chains
- Out of sync engine
- Wiring damage
- Malfunctioning camshaft or crankshaft sensors
- Out of date or internal damage on the ECM software
How to Check
As with most codes, checking for this error code requires an advanced scan tool and the expertise of a qualified technician to check and re-test the vehicle to verify the error. If the fault persists, then technicians will perform a thorough visual inspection or wiggle test until the error become more persistent.
Experienced DIYers may refer to an up-to-date user manual to diagnose the problem, but of course, it requires special tools.
To diagnose, the valve cover(s) or top timing cover should be removed to see any timing marks. Then, crankshaft pullet should be rotated clockwise until it timing hits 0˚ or TDC. If there aren’t any timing marks, then technicians may rotate the crankshaft to full 360 ˚. After rotating the crankshaft to TDC and the camshaft timing marks are in view, technicians can now verify the positions.
- For properly aligned camshafts, there’s a good chance the problem is in the crankshaft or the camshaft reluctor ring, which may be skewing the readings of CKP or CMP. Disassembly is needed to verify that reluctor rings are really properly aligned to their respective shafts.
- If camshafts are not properly aligned, then there must be a case of stretched or skipped timing belt o timing chain. Worn or loose belt tensioners can also lead to misalignment. This will require further disassembly to verify the chain’s condition, along with the tensioner function and measure the timing belt or chain.
How to Fix
For new vehicles with warranty on their powertrain, then by all means, take your vehicle to your dealer and have the error code fixed. Generally, the solution is pretty straightforward – alignment of misaligned chains and replacement of worn components.
If the timing belt or timing chain has skipped a tooth, then it should be properly reinstalled.
If the timing belt or timing chain is stretched, it should be replaced. The same goes to worn tensioners.
For GM engines, there’s a good chance there are revised and updated version of replacement components. You can refer to your factory service manual for your specific vehicle make and the specific troubleshooting steps.