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P21B4
NOx Adsorber - Over Temperature Bank 1
Generic · engine
Data confidence
65%
The control module detected that the NOx Adsorber temperature exceeded its permissible limit.
TuningBot DTC Database · v4.37.14
P21B4 NOx Adsorber - Over Temperature Bank 1
Generic (OBD-II) interpretation in the TuningBot DTC database.
What P21B4 means
Related and nearby codes
How to read P21B4
P
Powertrain: engine, transmission and driveline systems.
2
Generic SAE-standard code: same meaning on every make.
1B4
Specific fault index within the subsystem.
Frequently asked questions about P21B4
What does P21B4 mean?
NOx Adsorber - Over Temperature Bank 1. The control module detected that the NOx Adsorber temperature exceeded its permissible limit.
Is P21B4 generic or manufacturer-specific?
P21B4 is a generic OBD-II code: it has the same meaning on every make and model that follows the SAE standard.
Can TuningBot remove P21B4 at file level?
If the fault logic lives in the ECU calibration, yes: our DTC Removal file service disables the specific fault entry and, where the ECU needs it, corrects the checksum too. Not sure whether your case qualifies? Request a free assessment and our engineers will check your ECU file.
Other file services
Understand the system behind this code: SCR / AdBlue System