Heated Oxygen Sensor - Replacement/Checking: Overview
GROUP: 24NUMBER: 94-05
DATE: August 1, 1994
SUBJECT:
Heated Oxygen Sensor, Replacing
MODELS(s):
Golf III, Jetta III, Cabrio 2.0 Liter Engine all m.y.
Condition
A driveability complaint can lead to unnecessary replacement of the Heated Oxygen Sensor (HO2S).
The following complaints and/or observations may indicate a possible HO2S problem:
^ Hesitation
^ Vehicle loses power
^ Excessive visible exhaust smoke
^ Stalling and poor idle quality
^ CO outside of specified range
^ Malfunction Indicator Light (MIL), Check Engine Light, is on
^ VAG 1551 Scan Tool displays sensor malfunction
^ VAG 1551 Scan Tool displays Mixture control adjustment Diagnostic Trouble Code
Oxygen sensor related complaints can be caused by:
^ Incorrect wiring
^ Broken wires
^ Poor grounds
^ Corroded terminals
^ Oxygen sensor heater not being energized (Heater Relay not operating properly or supply Voltage interruption to the sensor)
^ Contaminated sensor
^ Malfunctioning engine Coolant Temperature sensor (could cause the same complaints as an Oxygen sensor)
^ Malfunctioning Engine Control Module