CLAAS Id773Ch / 773Ch (412 16) – ENG (A15): Temperature of cooled exhaust gases averagely high

The engine control system has detected that the exhaust gases passing through the Exhaust Gas Recirculation (EGR) cooler are not being cooled sufficiently before being reintroduced into the engine. To protect the engine, the engine calculator will automatically reduce engine power by 20% per minute until it reaches 50% of its nominal power.

• CLAAS Axion 800 series (810, 820, 830, 840, 850)
• CLAAS Arion 600 series (610, 620, 630, 640)
• CLAAS Jaguar forage harvesters

1. 1

   The cooled exhaust gas temperature sensor (B221): Check for accurate temperature readings, physical damage, or a short circuit.

2. 2

   The coolant level: Ensure the engine has adequate coolant to supply the EGR cooler.

3. 3

   The coolant thermostat: Verify that the thermostat is opening correctly and allowing coolant to circulate through the cooling system and EGR cooler.

4. 4

   The exhaust gas recycling (EGR) cooler: Check for internal blockages, soot buildup, or poor cooling efficiency.

1. 1

   Verify Coolant Levels

   Start by checking the engine coolant reservoir. If the level is low, top it up with the OEM-specified coolant and pressure-test the system to ensure there are no leaks.

2. 2

   Test the Thermostat

   If the coolant level is fine, monitor the engine coolant temperature. If the engine is running hotter than normal or coolant isn't circulating, remove and test (or replace) the coolant thermostat.

3. 3

   Inspect Sensor B221

   Locate the cooled exhaust gas temperature sensor (Component B221) on the EGR circuit. Inspect the wiring harness for shorts to ground or battery. Use a multimeter or diagnostic tool to verify if the sensor's resistance/temperature output is within spec. If the sensor is reading artificially high, replace it.

4. 4

   Service the EGR Cooler

   If the sensor and coolant system are functioning properly, the EGR cooler is likely restricted with soot or has failed internally, preventing heat transfer. Remove the EGR cooler, inspect for heavy carbon buildup, and clean or replace the cooler assembly as necessary.

5. 5

   Clear Codes and Test

   Clear the Id773Ch / 412 16 code from the ENG (A15) module. Run the machine under load to ensure the exhaust gas temperatures remain in the normal range and the ECU no longer derates the engine power.