Operation CHARM: Car repair manuals for everyone.
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General Remarks

NOTE: Removing fuses and disconnecting electrical components causes the powertrain control module (PCM) to show an error message. After measurement has been carried out this error message should be cleared from memory by connecting scan tool.

NOTE: Only check the compression pressure with the valves set to the prescribed clearance (if this can be adjusted).

Check the compression pressure with the engine at operating temperature.
Differing designs of compressor pressure recorder and varying starter motor speeds usually only make it possible to check that the compression is the same in all cylinders.