HEAT SINK AS-POSITIVE 5N5027 - Caterpillar

Probable Causes
Insulation on the exhaust duct (if equipped)
Diagnostic codes
Incorrect wiring for temperature sensors
Maintenance schedule
Low compression (cylinder pressure)
Electronic unit injectors
Individual malfunctioning cylindersRecommended Actions
Note: The procedures have been listed in order of probability. Complete the procedures in order.
Table 1
Troubleshooting Test Steps Values Results
1. Insulation on the Exhaust Duct (if equipped)
A. Check the insulation on the exhaust duct between the engine and the Clean Emissions Module (CEM). Make sure that insulation is not missing or damaged.
Codes
Result: The insulation is missing or damaged.
Repair: Repair or replace the insulation.
Result: The insulation is OK.
Proceed to Test Step 2.
2. Diagnostic Codes
A. Connect the electronic service tool to the diagnostic connector.
B. Check for active diagnostic codes.
C. Use the electronic service tool to perform a service regeneration.
D. Check for active diagnostic codes on the electronic service tool.
Diagnostic codes
Result: There are active diagnostic codes.
Repair: Investigate any active codes before continuing with this procedure. Refer to Troubleshooting, "Diagnostic Trouble Codes".
Result: There are no active diagnostic codes.
Proceed to Test Step 3.
3. Incorrect Wiring for Temperature Sensors
A. Check that the Diesel Oxidation Catalyst (DOC) inlet temperature sensor and DPF inlet temperature sensor wiring has not been switched.
Note: The engine may run without indicating a fault for many hours with this condition.
B. Check that the wiring for the DOC inlet temperature and the DPF inlet temperature sensor is connected to the correct ECM pins.
Refer to the Electrical Schematic for the application.
Wiring
Result: The wiring for the DOC inlet temperature sensor or the DPF inlet temperature sensor is incorrect.
Repair: Repair the faulty wiring or replace the faulty wiring.
Result: The wiring for the DOC inlet temperature sensor and the DPF inlet temperature sensor is OK.
Proceed to Test Step 4.
4. Maintenance Schedule
A. Check the maintenance schedule for the DPF. Refer to the Operation and Maintenance Manual, "Maintenance Interval Schedule".
Maintenance schedule
Result: The DPF is due for an ash service.
Repair: Perform an ash service. Refer to the Operation and Maintenance Manual, "Diesel Particulate Filter - Clean".
Result: The DPF is not due for an ash service.
Proceed to Test Step 5.
5. Low Compression (Cylinder Pressure)
A. Perform a compression test. Refer to Systems Operation, Testing, and Adjusting, "Compression - Test ".
Low compression
Result: Low compression is recorded on one or more cylinders.
Repair: Possible causes of low compression are shown in the following list:
Loose glow plugs
Faulty piston
Faulty piston rings
Worn cylinder bores
Worn valves
Faulty cylinder head gasket
Damaged cylinder head
Make any repairs, as necessary.
Result: No faults found.
Proceed to Test Step 6.
6. Individual Malfunctioning Cylinders
A. With the engine speed at a fast idle, use the electronic service tool to perform the manual "Cylinder Cut Out Test". As each cylinder is cut out, listen for a change in the sound from the engine. When a cylinder is cut out, there should be