Jetta III L4-2.0L (ABA) (1995)
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Technical Service Bulletin # 249405
Date: 940801
Heated Oxygen Sensor - Replacement/Checking
GROUP: 24
NUMBER: 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
Basic and Visual Checks
SERVICE
Note
All Repair Manual references refer to 04/94 Edition
Follow these steps to avoid unnecessary repairs when diagnosing suspected HO2S problems
Make sure you have enough information
