Some Diesel Particulate Filter (DPF) Sensor Boxes May Contain Loose Fittings that Connect to the Pressure Lines on the C7, C9, C13, and C15 On-highway Engines{1091, 1439, 7400} Caterpillar

On-highway Engine:

C13 (S/N: LEE1-UP)

C15 (S/N: SDP1-UP)

C7 (S/N: C7S1-UP)

C9 (S/N: C9S1-UP)

Introduction

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

Problem

Some Diesel Particulate Filter (DPF) sensor boxes may contain loose fittings on the pressure line.

Solution

If the check engine light illuminates with the fault code of 3251-18, DPF Has Differential Pressure Problem, perform the following procedure.

1. Disconnect the pressure lines from the pressure line fittings that are installed on the DPF sensor box.

2. Check in order to make sure that the DPF pressure line fittings cannot be loosened by hand. If the fittings are not tight, apply the proper torque.

   1. All straight line fittings and tee fittings use 11 N·m (100 lb in).

   2. All angled fittings use 8 N·m (71 lb in).

3. Reconnect the pressure lines to the DPF sensor box.

   1. Tighten the pressure lines to 8 N·m (71 lb in).

If the pressure line fittings are not loose, continue troubleshooting the 3251-18 code by using the troubleshooting guide for your engine.