P2D5AReductant Level Sensor A/B Correlation
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- P2D5A compares two level sensors of the diesel exhaust fluid system: each delivers a valid signal, yet together they describe a fill level that cannot be true. Tanks with several level contacts, or vehicles with a main and an auxiliary tank, can cross-check their sensors this way. No manufacturer documents P2D5A on an official public source. GM's 2014 diesel tables show the idea under P203B: the module pulses three discrete level contacts and reports a fault after 5 s, Type B, when the readings form an impossible combination, for instance sensor 2 in its 0 to 1.7 V band while sensor 1 sits at 1.71 to 3.56 V. California requires the level sensor to be monitored as input to driver inducement. A wrong reading can bring early warnings or the inducement countdown.
- What you may notice
- Implausible or jumping DEF level display
- MIL and DEF warning message
- Possible inducement countdown despite sufficient fluid
- Likely causes
- LikelyOne level sensor failed or contaminated
- PossibleUrea crystals or deposits on the sensing elements
- PossibleCorrosion or poor contact at the tank sensor connector
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €80 – €1,200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.