P124F

4BF0 - P124F

Information saved in
DDE

Fault code
4BF0 - P124F

Fault text
DDE: Nitrogen oxide sensor after SCR catalytic converter,
NOx signal: NOx signal invalid for too long

Fault description
The NOx status signal of the NOx sensors behind SCR
converter reports a malfunction.
This is the case when at least one of the following
conditions is applicable:
- The debounced CAN status of the raw NOx sensor value is
invalid ==0.
- There is an NOx signal error is disabled
- Lambda signal from NOx sensor 2 (behind SCR converter)
is not present, lean exhaust gas ==0.

Condition for fault identification
Test condition:
The error check runs when compliance with the following
conditions is present ( ==1):
- A positive flank of the signal has been detected.
- This is a case of lean combustion == 1.
- The NOx sensor diagnosis is enabled ==1
- No plausibility or electrical error related to the NOx sensor
has occured is not disabled.
- Engine status ==RUNNING.
The error check proceeds continuously according to the
programmed process grid.
Voltage condition:
The error check runs when compliance with the following
conditions is present ( ==1):
- A positive flank of the signal has been detected.
- This is a case of lean combustion == 1.
- The NOx sensor diagnosis is enabled ==1
- No plausibility or electrical error related to the NOx sensor
has occured is not disabled.
- Engine status ==RUNNING.
The error check proceeds continuously according to the
programmed process grid.

Condition for fault memory entry
Event debounced (10)

Action in service
1. Check wires and plug connections.
2. If wiring and plug connections are OK:
3. Check NOx sensor 2 (behind SCR converter).

Fault effect and breakdown warning
-

Driver information
Warning light:
MIL

Service instruction
Replace NOx sensor 2 (behind SCR catalyst).