Volkswagen Golf 1999 Service Manual page 679

Measured value (data) blocks
Evaluating display group 33, display zone 1 - Oxygen Sensor (O2S) control before
Three Way Catalytic Converter (TWC)
Appears on
display
Outside
tolerance
range
http://ebahn.bentleypublishers.com/vw/servlet/Display?action=Next&type=repair&id=...
Possible cause
Minus range: Mixture too rich,
Oxygen Sensor (O2S) control
weakens mixture
Positive range: Mixture too lean,
Oxygen Sensor (O2S) control
enriches mixture
Oxygen Sensor (O2S) learned
value on limit
Fuel injector faulty
Unmetered air
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Corrective action
- Wait 30 seconds until
display has stabilized
- Check Oxygen Sensor
(O2S) learned value in
display group 32
- Check fuel injectors
Page 24-97
- Check intake air system for
leaks Page 24-121
01-224
12/2/2005