P1621 – BMW DTC

BMW DTC P1621 – Map Cooling Thermostat Control Circuit Intermittent

DTC P1621 meaning on BMW

DTC P1621 on a BMW indicates an issue with the Map Cooling Thermostat Control Circuit being intermittent. This means that there is a problem with the circuit that controls the thermostat responsible for regulating the engine coolant temperature based on the map sensor input.

BMW DTC P1621 symptoms

Symptoms of DTC P1621 on a BMW may include:

• Engine overheating
• Decreased fuel efficiency
• Check Engine Light (CEL) illuminated on the dashboard
• Engine running too cold or too hot

BMW DTC P1621 causes

The potential causes of DTC P1621 on a BMW include:

• Faulty map cooling thermostat
• Wiring or connector issues in the thermostat control circuit
• Defective engine coolant temperature sensor
• ECU (Engine Control Unit) malfunction

BMW DTC P1621 seriousness

Ignoring DTC P1621 on a BMW can lead to serious engine problems such as overheating, which may cause engine damage or even failure. It is important to address this issue promptly to prevent further complications.

How to diagnose DTC P1621 on BMW

To diagnose DTC P1621 on a BMW, you can perform the following steps:

1. Use a diagnostic scanner to retrieve the fault codes from the ECU
2. Inspect the map cooling thermostat and its wiring for any visible damage
3. Check the engine coolant temperature sensor for proper operation
4. Test the thermostat control circuit for continuity and proper voltage

How to fix DTC P1621 on BMW

To fix DTC P1621 on a BMW, you may need to:

1. Replace the faulty map cooling thermostat
2. Repair or replace any damaged wiring or connectors in the thermostat control circuit
3. Replace the engine coolant temperature sensor if necessary
4. If the ECU is found to be faulty, it may need to be reprogrammed or replaced

How to erase DTC P1621 on BMW

To erase DTC P1621 on a BMW, you can:

1. Use a diagnostic scanner to clear the fault codes stored in the ECU
2. After fixing the underlying issue, drive the vehicle to allow the ECU to perform a self-check and verify that the fault code does not return