Operation CHARM: Car repair manuals for everyone.

Ignition Timing: Description and Operation

- Engine idle speed and ignition timing are not adjustable.

- CO content is regulated by Oxygen Sensor (O2S) control. Malfunctions in Oxygen Sensor control are detected by the On Board Diagnostics (OBD) program using the VAG 1551 Scan Tool (ST), and stored in Diagnostic Trouble Code (DTC) Memory in the Motronic Engine Control Module (ECM).