Knock Sensor Inoperative - DTC 22 or 28

[How-To Doc]

Knock Sensor Inoperative - DTC 22 or 28

Author: Subaru

NUMBER: 11-46-95

DATE: 10/11/95

APPLICABILITY
1990 THROUGH 1995 LEGACY 2.2L
1992 THROUGH 1995 SVX 3.3L
1995 IMPREZA 2.2L

SUBJECT:
KNOCK SENSOR

It has been determined that a small percentage of the applicable vehicles may experience improper operation of the Knock Sensor assembly due to breakage of an internal lead wire. Should this occur, the driver will experience illumination of the Malfunction Indicator Light (MIL or "Check Engine" light) and a slight reduction in engine power due to retarded ignition timing ("fail safe" mode.) Should the above condition occur, the technician will find diagnostic trouble codes as follows:

Legacy 2.2L 1990-1994 MY
CODE 22

Legacy/Impreza 2.2L 1995 MY
OBD-II System
CODE P0325

SVX 3.3L 1992-1995 MY
CODE 22 - Right Knock Sensor # 1
CODE 28 - Left Knock Sensor # 2

If you encounter a complaint with the codes listed above, it will be necessary to replace the affected Knock Sensor with a new one - part number 22060AA031. The color of the connector on the replacement knock sensor has changed from gray to white for positive identification. When servicing SVX models, replace both knock sensors even if the second diagnostic trouble code has not illuminated. After the repair, clear the diagnostic trouble code(s). In the unlikely event that the Malfunction Indicator Light remains on or the above specified diagnostic trouble code(s) reappear, refer to the applicable service manual for proper diagnostics. Installation of the Knock Sensor can be claimed under the terms of the Subaru Emission Control Systems warranty.

Applicability: 1990-1995 Legacy/1995 Impreza 2.2L

FAILURE CODE.......OPERATION #........LABOR DESCRIPTION..............LABOR TIME

KNOCK SENSOR........A145-581.......KNOCK SENSOR - REPLACE
....UEA-48....................................(INCLUDES ACCESSING .................0.3
...............................................DTC USING SELECT MONITOR)

Note: Refer to the applicable service manual for 1990-1995 Legacy and 1995 Impreza 2.2L knock sensor replacement procedure.

Applicability: 1992-1995 SVX 3.3L

FAILURE CODE.......OPERATION #......LABOR DESCRIPTION.................LABOR TIME

KNOCK SENSOR........A145-581.....KNOCK SENSOR BOTH - REPLACE........ 0.7
UEA-48......................................(INCLUDES ACCESSING DTC
............................................... USING SELECT MONITOR)

Note: Refer to revised 1992-1995 SVX 3.3L knock sensor replacement information on the reverse side.

Revised SVX Service Manual Removal And Replacement Procedures For Knock Sensors Number 1 (RH) and Number 2 (LH). This information supersedes the Removal And Replacement Procedures listed in the SVX Service Manuals.

Removal

1) Disconnect negative battery cable
2) Remove both plastic intake manifold covers
3) Remove the alternator

Left Sensor Replacement

1) Disconnect the knock sensor wire connector.
2) Note the orientation of the knock sensor on the engine block and install the new sensor in the same position.
3) Use a 3/8 drive ratchet, 12 inch extension and a 12 mm flex socket to access the knock sensor mounting bolt.
4) Insert the extension and socket assembly through the left side of the hole in the center of the intake manifold, refer to the illustration below.

Note: When removing the knock sensor, the wire connector is tight but will pass between the coolant crossover manifold and the engine block.

Right Sensor Replacement

1) Disconnect the knock sensor wire connector.
2) Note the orientation of the knock sensor on the engine block and install the new sensor in the same position.
3) Use a 12 mm boxed end wrench to access the knock sensor mounting bolt from the front of the engine.

Installation

1) Install in reverse order of the removal procedures.
Note: Torque the knock sensor mounting bolt(s) for all applicable models to 17.4 +/- 2.1 ft-lb.

Note: Refer to the applicable service manual for proper knock sensor mounting bolt torque.


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