Vanagon 2WD L4-2109cc 2.1L (1986)
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Disconnect RPM signal wire
Note: As of 9-87 production this connection has moved to the right side of the engine compartment (in front of the air flow sensor).
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Disconnect oxygen sensor
Note: The oxygen sensor must be disconnected with the ignition OFF to cancel the memory in the control unit.
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Start engine
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Hold disconnected (green) oxygen sensor wire from the control unit to ground
CO content must increase
If NO
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Check wire connection on control unit, refer to Fuel Delivery and Air Induction - Testing and Inspection - Procedures - Electrical Testing -
Ignition and Injection System See: Powertrain Management/Fuel Delivery and Air Induction/Testing and Inspection, test step II
If OK
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Replace control unit and recheck
Note: If test step I is not OK but test step II is OK, the oxygen sensor is defective.