P2457

4873 - P2457

Information saved in
DDE

Fault code
4873 - P2457

Fault text
Exhaust gas recirculation cooling, plausibility:

Fault description
Monitoring EGR cooler bypass valve.
The temperature downstream from the EGR cooler bypass
valve is stored at specific times.
The stored temperatures are employed to generate two
temperature gradients.
An activation signal is transmitted to the EGR cooler bypass
valve while the temperature gradients are being generated. If
the EGR cooler bypass valve is in good condition then a
temperature variation must be apparent. In contrast, if the
EGR cooler bypass valve is defective then virtually no
variation in the temperature gradient will be apparent.
The diagnostic trouble code is logged when the absolute
difference between the temperature gradients falls below the
limit value 5 K.

Condition for fault identification
Test condition:
The check runs every 100 ms when all of the enable
conditions are present:
- For a duration of 1000 ms the specified torque gradient is
below 4 Nm/s.
- The rpm is within the limits 980 1/min and 590 1/min.
- For the duration 1000 ms the modeled exhaust-gas
recirculation rate is greater than 21.
- The engine is running at idle.
- The air mass control/EGR rate control is active and no
deactivation conditions are active.
- The vehicle speed is less than 3 km/h.
- The engine is not in the regeneration mode.
- The coolant temperature is between 60 �C and 110 �C.
- The modeled exhaust-gas temperature is greater than
EGRClg_tExhMnfUsThresLo_C.
- The temperature behind the EGR cooler is below the limit
value 1 K/s.
- The injection rate is between 6 mg/hub and 100 mg/hub.
Voltage condition:
The check runs every 100 ms when all of the enable
conditions are present:
- For a duration of 1000 ms the specified torque gradient is
below 4 Nm/s.
- The rpm is within the limits 980 1/min and 590 1/min.
- For the duration 1000 ms the modeled exhaust-gas
recirculation rate is greater than 21.
- The engine is running at idle.
- The air mass control/EGR rate control is active and no
deactivation conditions are active.
- The vehicle speed is less than 3 km/h.
- The engine is not in the regeneration mode.
- The coolant temperature is between 60 �C and 110 �C.
- The modeled exhaust-gas temperature is greater than
EGRClg_tExhMnfUsThresLo_C.
- The temperature behind the EGR cooler is below the limit
value 1 K/s.
- The injection rate is between 6 mg/hub and 100 mg/hub.

Condition for fault memory entry
-

Action in service
1. Check vacuum supply to the EGR cooler's bypass valve
(vacuum lines and switch valve).
2. If the vacuum supply is in satisfactory condition:
Replace the EGR cooler (the bypass valve's return spring
may be defective).

Fault effect and breakdown warning
Proceed to the nearest BMW Service facility.

Driver information
Warning light:
MIL

Service instruction
none