Exhaust emission and idle speed check (Every 12 months - regardless of mileage)

Routine maintenance and servicing / Exhaust emission and idle speed check (Every 12 months - regardless of mileage)

1 Experienced home mechanics equipped with an accurate tachometer and a carefullycalibrated exhaust gas analyser may be able to check the exhaust gas CO content and the engine idle speed; if these are found to be out of specification, then the vehicle must be taken to a suitably-equipped VW dealer for assessment. Idle speed and exhaust CO adjustment screws are provided (multi-point fuel-injected models only - refer to Chapter 4B for details), but adjustment will not be possible if the engine management system has detected a fault in one of the fuelling or ignition system components. Under these circumstances, the engine management system will enter a ‘back-up’ mode and will not respond to adjustment. For this reason, all fault codes must be erased from the engine management system memory before the idle speed and exhaust CO settings can be checked and adjusted - this operation must be carried out by a VW dealer equipped with the required test equipment (see Section 13).

Caution: inaccurate CO adjustment may cause overfuelling and the risk of serious catalytic converter damage.