SCR system and AdBlue
P202A, P203A–P203F and P205B: AdBlue tank and level
This code family concerns functions at the reductant tank: heating, level and temperature measurement. The exact code determines whether the ECU is reporting a circuit problem, a plausibility issue or an assessed fluid level.
At a glance
What the codes tell you
- P202A
- Reductant tank heater—control circuit/open.
- P203A
- Reductant level sensor—circuit.
- P203B
- Reductant level sensor—range/performance.
- P203C
- Reductant level sensor—signal low.
- P203D
- Reductant level sensor—signal high.
- P203E
- Reductant level sensor—intermittent/erratic signal.
- P203F
- Reductant level too low.
- P205B
- Reductant tank temperature sensor—range/performance.
How the entries differ
- P202A concerns the tank-heater control circuit; P205B concerns the tank-temperature range/performance assessment.
- P203A to P203E distinguish level-sensor circuit, plausibility and signal-level conditions.
- P203F reports a reductant level assessed as too low.
What is not yet established
- A warning after refilling does not prove an incorrect fill quantity or a failed tank.
- Tank design, integrated sensors and any required initialisation vary by vehicle.
- The code describes the control unit’s assessment. It determines neither which component needs replacing nor the repair required.
- Manufacturer-specific descriptions, status, freeze-frame data and live readings can materially change the interpretation.
Diagnostic information that helps next
A reliable assessment does not consider the code in isolation. The following information turns a number into a fault condition that can be investigated:
- Complete dashboard message and displayed remaining distance
- Actual quantity added and when the tank was filled
- Level, temperature and heater readings from the diagnostic tool
- Power supply, connectors and the status of any required initialisation
More codes for this system
Frequently asked questions about P202A, P203A, P203B, P203C, P203D, P203E, P203F, P205B
What do fault codes P202A, P203A, P203B, P203C, P203D, P203E, P203F, P205B mean?
P202A: Reductant tank heater—control circuit/open. P203A: Reductant level sensor—circuit. P203B: Reductant level sensor—range/performance. P203C: Reductant level sensor—signal low. P203D: Reductant level sensor—signal high. P203E: Reductant level sensor—intermittent/erratic signal. P203F: Reductant level too low. P205B: Reductant tank temperature sensor—range/performance.
Which component needs replacing for P202A?
The code does not determine that. The full diagnostic description, fault status, freeze-frame data, live readings and vehicle-specific system checks determine the appropriate repair.
What information helps with diagnosis?
Useful information includes Complete dashboard message and displayed remaining distance, Actual quantity added and when the tank was filled, Level, temperature and heater readings from the diagnostic tool, Power supply, connectors and the status of any required initialisation.
Traceable sources
Sources and scope
The descriptions are our own factual explanations of standardised generic OBD definitions. Manufacturer-specific P1xxx codes and differing manufacturer descriptions are not given blanket interpretations here.