New Holland ENG 3771 – Engine Control Unit (ECU) / EDC (Electronic Diesel Control): Oxidation Catalyst: Up and down stream temperature sensors in Oxidation catalysts exchanged

The engine control system has detected an implausible temperature gradient across the Diesel Oxidation Catalyst (DOC). The temperature readings from the upstream (inlet) and downstream (outlet) Exhaust Gas Temperature (EGT) sensors are inverted, indicating the electrical connectors were swapped or the physical sensors were installed into the wrong bungs.

• CR9090
• CX8080 Elevation
• CX8090 Elevation
• T5
• T6
• T6.145
• T6.180
• T7
• T7.210
• T7.270
• T8 series
• L223
• L225
• L230
• C227
• C232
• C238
• Speedrower 130
• Speedrower 160
• Speedrower 200
• Speedrower 220
• Speedrower 240
• Speedrower 260
• W50C through W300C

1. 1

   Visually inspect the wiring harness for the upstream and downstream EGT sensors on the DOC canister to verify they are plugged into the correct connectors

2. 2

   Connect the CNH Electronic Service Tool (EST) or compatible scanner and monitor live data for DOC Inlet Temperature and DOC Outlet Temperature

3. 3

   Perform a cold start test: verify the upstream (inlet) temperature rises first and faster than the downstream (outlet) temperature

1. 1

   Cool Down

   Turn off the machine and allow the exhaust system to cool completely to prevent severe burns.

2. 2

   Locate Sensors

   Locate the Diesel Oxidation Catalyst (DOC) canister in the exhaust stream. Identify the two temperature sensors (one before the catalyst, one after).

3. 3

   Swap Connectors

   Disconnect the electrical connectors for both the upstream and downstream sensors. Swap the connections so that they are plugged into their correct respective harness leads.

4. 4

   Physical Swap (If necessary)

   If the wiring harness cannot physically reach the swapped position, use a wrench to carefully remove both sensors, apply a high-temperature anti-seize compound to the threads, and reinstall them in the correct ports.

5. 5

   Clear Codes

   Turn the key on and use your diagnostic tool to clear the ENG 3771 fault code, or perform a few standard key cycles to allow the EDC to recognize the corrected sensor orientation and change the code from Active to Inactive.