496B

496B - P229F

Information saved in
DDE

Fault code
496B - P229F

Fault text
NOx sensor after DeNOx catalytic converter, plausibility
NOx :

Fault description
Monitoring of NOx offset learning function at NOx sensor 2
(behind SCR). The error is recognized when the learned
NOx offset value ppm rises above the limit value 20 ppm.

Condition for fault identification
Test condition:
Continuous according to defined time grid when the offset
test is enabled:
- Enabled in application 0== 0.
- The test is executed on a falling flank of .
and when the following conditions are satisfied:
- The absolute difference between the maximum ppm and
minimum ppm NOx offset value is less than 2 ppm.
- ppm is greater than 0 ppm.
- The averaged offset value ppm lies within the monitoring
window -30 ppm and 30 ppm.
Voltage condition:
Continuous according to defined time grid when the offset
test is enabled:
- Enabled in application 0== 0.
- The test is executed on a falling flank of .
and when the following conditions are satisfied:
- The absolute difference between the maximum ppm and
minimum ppm NOx offset value is less than 2 ppm.
- ppm is greater than 0 ppm.
- The averaged offset value ppm lies within the monitoring
window -30 ppm and 30 ppm.

Condition for fault memory entry
Event debounced (1)

Action in service
Determine whether multiple occurences of the error are
present. If the error occurs once then the DTC can simple be
deleted. Respond to multiple occurences by replacing the
NOx sensor.

Fault effect and breakdown warning
-

Driver information
Warning light:
MIL

Service instruction
-