OBD fault code library
Look up any P or U code to see what it means, what causes it, the parts involved and how it gets fixed.
Free on OBD DashX
Looking for real-world repair data?
OBD DashX shows which problems come with each code, how often they show up in other vehicles, and how to fix them — step by step.
- Real-world fix data
- How often it happens
- Step-by-step repairs
Fault codes
P1401
Differential Pressure Feedback Electronic Sensor Circuit High Voltage
Mercedes Benz
Auxiliary Emissions Control
Medium severity
P1409
EGR Vacuum Regulator Solenoid Circuit Malfunction
Mercedes Benz
Auxiliary Emissions Control
Medium severity
P1411
Secondary Air Injection System Malfunction
Mercedes Benz
Auxiliary Emissions Control
Medium severity
P1438
A/C Evaporator Air Temperature Circuit Range/Performance
Mercedes Benz
Auxiliary Emissions Control
High severity
P1444
Evaporative Emission Canister Purge Valve Malfunction
Mercedes Benz
Auxiliary Emissions Control
Low severity
P1452
Secondary Air Injection System Circuit Open
Mercedes Benz
Auxiliary Emissions Control
Medium severity
P1454
Exhaust Gas Temperature Sensor Short 1 to Ground
Mercedes Benz
Vehicle Speed and Idle Control System
Medium severity
Scan your own car
Read and clear fault codes, live data and service resets with the CaRPM app.