HEGO Sensor - Diagnosis, Manual Revision: Overview

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ENGINE/EMISSIONS DIAGNOSIS SHOP MANUAL - 1990 - 7.5L ENGINE HEGO SENSOR REVISED FROM 3-WIRE TO 4-WIRE - PINPOINT TEST SCHEMATICS UPDATED

Article No. 90-12B-13

LIGHT TRUCK: 1990 BRONCO, ECONOLINE, F-150, F-250, F-350

ISSUE: The 3-wire HEGO sensor has been replaced with a 4-wire sensor on 1990 7.5L EFI truck. The 1990 4.9L EFI truck 4-wire sensor is not grounded to SIG RTN in the harness as shown in the 1990 Engine/Emissions Diagnoisis Shop Manual.

ACTION: Refer to the pages following this TSB article for the updated schematics and pinpoint test procedures.

OTHER APPLICABLE ARTICLES: NONE
WARRANTY STATUS: INFORMATION ONLY
OASIS CODES: 2800