Manufacturer Code Charts: 4501

4501 - P0401

Information saved in
DDE

Fault code
4501 - P0401

Fault text
DDE: Exhaust-gas recirculation, control deviation: Air mass
too high/negative control deviation

Fault description
The diagnostic trouble code is logged in the ECU when the
exhaust-gas recirculation system's negative control deviation
falls below a limit defined based on the operating point.

Condition for fault identification
Test condition:
The test runs every 20 ms when the exhaust-gas
recirculation control system is activated, the monitoring
system is enabled and no other system fault is present.
Voltage condition:
The test runs every 20 ms when the exhaust-gas
recirculation control system is activated, the monitoring
system is enabled and no other system fault is present.

Condition for fault memory entry
Debounce (7500 ms)

Action in service
Check the following potential problem sources:
1. Leaks in mass airflow system on engine side of
compressor
2. Leaks in exhaust system on engine side of turbine
(combined with mass airflow plausibility errors).
3. Throttle valve defect (in combination with throttle valve
faults).
4. Defective EGR valve (in combination with EGR valve
errors).
5. Defective turbocharger (in combination with turbocharger
faults).
6. Severe EGR cooler soot accumulation.
Applies to engines with single-stage boost: Conduct mass
airflow system test.

Fault effect and breakdown warning
It is possible to continue driving the vehicle, emissions
deteriorate.
Proceed to the nearest BMW Service facility.

Driver information
Warning light:
MIL

Service instruction
Note collateral effects on boost-pressure control (faults in
the exhaust-gas recirculation system can affect the boost-
pressure control system).
Check diagnostic trouble codes for the named components.