
877 – AL Flap Bypass A Ref learn failed
Cause
Corrective action
Fast reference run of EGR
shutoff flap (M52) (executed
after each ECU restart) faulty.
1. Check charge state of the batteries (plant side).
2. Check operation of bypass flap (→ Page 122).
3. Contact Service.
879 – AL Flap Dispenser Ref learn failed
Cause
Corrective action
Fast reference run of donor flap
(M55) (executed after each ECU
restart) faulty.
1. Check charge state of the batteries (plant side).
2. Check operation of donor flap (→ Page 122).
3. Contact Service.
953 – AL Lambda value invalid
Cause
Corrective action
Status information of lambda
sensor (B89), generated in case
of short-term implausible
measured values or sensor
defect.
1. Acknowledge alarm.
2. Replace lambda sensor (→ Page 168).
3. Contact Service.
954 – AL NOx value invalid
Cause
Corrective action
Status information of NOx
sensor (B88), generated in case
of short-term implausible
measured values or sensor
defect.
1. Acknowledge alarm.
2. Replace NOx sensor (→ Page 166).
3. Contact Service.
956 – AL p5 ctrlvar limit min active
Cause
Corrective action
The charge-air controller
attempts to set a set value but
has reached the lower limit. The
bypass flap (M52) is fully open.
1. Check operation of bypass flap (→ Page 122).
2. Contact Service.
957 – AL p5 ctrlvar max BOI min active
Cause
Corrective action
Emission-related alarm.
The charge-air controller
attempts to set a set value but
has reached the upper limit. The
bypass flap (M52) is fully closed.
The retardation of the start of
injection has reached its
maximum value.
1. Check air filter (plant side) for contamination.
2. Check operation of bypass flap (→ Page 122).
3. Exhaust turbocharger (LP), turbine housing check (→ Page 101).
4. Exhaust turbocharger (HP), check turbine housing (→ Page 109).
5. Contact Service.
66 | Troubleshooting | MS150096/03E 2015-04
TIM-ID: 0000029153 - 010