Case IH P90 – Engine Control Unit (ECU): Fuel Injection Pump Temperature, Data Valid But Above Normal Range

This code indicates that the fuel temperature sensor is functioning and sending a valid signal to the computer, but the temperature of the diesel fuel at the injection pump has exceeded the normal operating threshold. This can be caused by a failing sensor sending skewed resistance values, or an actual overheating condition in the fuel system (such as a fuel restriction or lack of fuel cooling).

• MXM
• MXM 120
• MXM 130
• MXM 140
• MXM 155
• MXM 175
• MXM 190
• Maxxum MX Series
• CX Series
• CS Series
• C Series

1. 1

   Inspect the wiring harness and the electrical connector at the fuel temperature sensor for chafed wires, corrosion, or a short to ground, which can cause skewed temperature readings.

2. 2

   Disconnect the sensor and measure its resistance with a multimeter. The resistance should change smoothly as the engine warms up. If there is no resistance (open circuit) or it is completely shorted, the sensor is faulty.

3. 3

   Verify that the injection pump is not actually overheating. Check for restricted fuel filters, pinched return lines, or low fuel levels, as diesel fuel acts as a coolant for the injection pump.

1. 1

   Preparation

   Turn off the tractor, engage the parking brake, and allow the engine and fuel system to cool completely.

2. 2

   Locate the Sensor

   Locate the fuel temperature sensor. On most of these engines, it is located on the left side of the engine, threaded directly into the fuel injection pump housing or the fuel rail.

3. 3

   Disconnect

   Carefully unplug the electrical connector from the sensor.

4. 4

   Clean

   Clean the area around the sensor base thoroughly to prevent any dirt or debris from falling into the injection pump when the sensor is removed.

5. 5

   Remove

   Unscrew the old sensor using a wrench or deep socket. Have a rag ready, as a small amount of diesel fuel may leak out.

6. 6

   Install

   Thread the new fuel temperature sensor into the housing. Tighten it to the manufacturer's torque specification (do not overtighten, as the brass threads can break).

7. 7

   Reconnect

   Plug the electrical connector back into the new sensor, ensuring it clicks into place.

8. 8

   Clear Codes

   Turn the ignition on. In most Case IH / CNH systems, general error codes clear automatically from the active display once the underlying hardware issue is resolved and a valid temperature reading is detected.