NOx Sensor Location Identification for C3.4B Engines Used on Certain Paving Compactors {108F, 1091} Caterpillar

Engine Package

3.4B (S/N: CN51-UP)

Vibratory Asphalt Compactor

CCS7 (S/N: 4B21-UP)

Vibratory Soil Compactor

CP44B (S/N: 4P41-UP)

CS44B (S/N: CS31-UP)

Introduction

The problem that is identified below does not have a known permanent solution. Until a permanent solution is known, use the solution detailed below to correct the issue.

Problem

The machine NOx sensors may be incorrectly located when performing Step 2 of the "NOx Conversion Is Low" 4364-17 diagnostic troubleshooting procedure in media number UENR4499 for C3.4B engines. The troubleshooting procedure notes the black wire insulated NOx sensor (461-5511) should be positioned after the engine and the gray wire insulated NOx sensor ( 461-5585) should be positioned on the tailpipe.

Certain machines have been manufactured with the 461-5585 gray wire insulated NOx sensor located at the engine-out and the 461-5511 black wire insulated NOx sensor located at the tailpipe-out. The aftertreatment system is not affected because these specific NOx sensors are similar except for the wire insulation color. The machine harness configuration determines the actual NOx sensor locations for the aftertreatment controller.

Solution

Caterpillar is aware of this problem, and recommending to follow the below information when troubleshooting the NOx sensor location on the above listed machines.

Connect the engine-out NOx sensor to the machine harness with 5 leads regardless of wire insulation color. Connect the tailpipe-out NOx sensor machine harness with 4 leads regardless of wire insulation color. Refer to Illustration 1, Illustration 2, Illustration 3, and Illustration 4 for correct location of NOx sensors.

Illustration 1	g06148105
(A) Machine harness with 5 leads connector, attached to engine-out NOx sensor

Illustration 2	g06148115
(B) Location of Tailpipe-out NOx sensor (C) Location of Engine-out NOx sensor

Illustration 3	g06148117
(B) Location of Tailpipe-out NOx sensor in machine view

Illustration 4	g06148121
(C) Location of Engine-out NOx sensor in machine view