PIN AS 2512542 - Caterpillar

Note: This procedure is only applicable to engines equipped with a wall flow Diesel Particulate Filter (DPF) and a DPF differential pressure sensor.This procedure covers the following diagnostic codes:
Table 1
Diagnostic Trouble Codes for the DPF Differential Pressure
J1939 Code Description Notes
3251-7 Particulate Trap Differential Pressure : Not Responding Properly The Electronic Control Module (ECM) detects the following conditions:
The measured differential pressure from the DPF differential pressure sensor is invalid.
The battery voltage is at least 10 VDC.
This fault can be caused by damaged or blocked pipes to the DPF differential pressure sensor.
If equipped, the warning lamp will come on. The engine will be derated.
3251-10 Particulate Trap Differential Pressure : Abnormal Rate of Change The ECM detects the following conditions:
The differential pressure across the DPF does not drop below 2.5 kPa (0.36 psi) after the engine has stopped.
This code will be active when the defect has been detected for at least 6 seconds.
The battery voltage is at least 10 VDC.
If equipped, the warning lamp will come on. The engine will be derated.
3251-17 Particulate Trap Differential Pressure : Low - least severe (1) The ECM detects the following conditions:
There is no differential pressure across the DPF for at least 100 seconds.
The battery voltage is at least 10 VDC.
The engine will be derated.
The fault will be cleared if the differential pressure is within the acceptable range for at least 10 seconds.
3251-18 Particulate Trap Differential Pressure : Low - moderate severity (2) The Electronic Control Module (ECM) uses the Diesel Particulate Filter (DPF) differential pressure sensor to monitor the soot load in the DPF. An excessive accumulation of soot in the DPF can be caused by the following faults:Probable Causes
Diagnostic codes
Exhaust leaks
Connections to the DPF differential pressure sensor
Incorrect installation of the DPF
Faulty DPF differential pressure sensorRecommended Actions
Note: The procedures have been listed in order of probability. Complete the procedures in order.
Table 2
Troubleshooting Test Steps Values Results
1. Diagnostic Codes
A. Establish communication between -the electronic service tool and the Electronic Control Module (ECM).
B. Check for active diagnostic codes. Check specifically for an active 3251-3 or 3251-4 diagnostic code.
Diagnostic codes
Result: A 3251-3 or 3251-4 diagnostic code is active
Refer to Troubleshooting, "Sensor Signal (Analog, Active) - Test" before returning to this procedure.
Result: A related diagnostic trouble code is not active or logged.
Proceed to Test Step 2.
2. Exhaust Leaks
A. Thoroughly inspect the exhaust duct between the engine and the DPF for leaks. Ensure that all connections are secure and no leaks are present.
Exhaust leaks
Result: There are leaks in the exhaust system.
Make any necessary repairs.
Result: The exhaust system is OK.
Proceed to Test Step 3.
Illustration 1 g02726855
Typical view of the DPF differential pressure sensor
(1) Connection to the DPF inlet
(2) Connection to the DPF outlet
Table 3
Troubleshooting Test Steps Values Results
3. Connections to the DPF Differential Pressure Sensor
A. Thoroughly inspect the following components for blockages and/or damage:
Connection (1) on the DPF differential pressure sensor
Connection (2) on the DPF differential pressure sensor
The pipes between the DPF differential pressure sensor and the DPF
The pipe connections on the DPF for the differential pressure sensor
Damage and/or blockages
Result: One