Volkswagen Passat 1995 Official Factory Repair Manual page 1872

Multiport fuel injection and ignition system
http://ebahn.bentleypublishers.com/vw/servlet/Display?action=Goto&type=repair&id=VW.B4.FU07.24.1
Checking basic voltage
- Disconnect 4-pin connector -1- (black) to HO2S -
G39- (before three way catalytic converter).
- Connect multimeter with test leads from VW 1594
to measure voltage at ECM connector terminals 3
and 4.
- Start engine and measure basic voltage.
Specification: 0.40-0.50 volts
- Switch ignition off.
If the specification is not attained:
- Check HO2S wiring
If the specification is attained:
- Replace HO2S -G39- (before three way catalytic
converter).
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12/6/2004
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