New Holland ENG 3668 – Engine Control Unit (ECU / EDC): EGR Over Temperature Error for H-bridge

The H-bridge electronic motor-driver circuit inside the ECU that commands the EGR valve has overheated. This is typically caused by excessive electrical current draw due to a mechanically stuck/binding EGR valve, a short in the wiring harness, or an internal ECU hardware failure.

• L220
• SR175
• Compact Track Loaders (CTLs)
• B90B
• B100B
• W50BTC
• W60BTC
• W70BTC
• W80BTC

1. 1

   Check for intermittent failure by clearing the code and operating the machine to see if it is a hard fault or a temporary glitch

2. 2

   Inspect the EGR valve for heavy soot buildup, carbon packing, or mechanical binding

3. 3

   Test the wiring harness between the EGR valve and the Engine ECU for shorts to ground or shorts to battery

4. 4

   Measure the resistance of the EGR valve motor to ensure it has not shorted internally

1. 1

   Clear and Retest

   Clear the DTCs using the New Holland Electronic Service Tool (EST). Run the engine. If the code does not return, return the machine to service.

2. 2

   Clean/Replace EGR Valve

   If the code returns and the EGR valve is found to be mechanically stuck or electrically shorted, replace the EGR valve assembly.

3. 3

   Replace Engine Controller

   If the EGR valve and wiring harness test perfectly fine but the code remains active, the H-bridge circuit inside the ECU is permanently damaged. Replace the Engine Controller.

4. 4

   Restore Self-Learning Parameters

   Whether you replace the EGR valve or the Engine ECU, connect the New Holland EST laptop and follow the appropriate service tool procedure to restore self-learning parameters so the ECU can learn the end-stops of the new EGR valve.