Reductant Tank Temperature/Fuel Temperature Correlation
After a long key-off soak the AdBlue/DEF tank temperature and the fuel tank temperature should read close to each other (both at ambient). The ECM detects an implausible spread, which usually means one of the two sensors drifts, is wired wrong, or has a heat source nearby that the plausibility model does not account for.
Affected components
- Reductant tank temperature sensor
- Fuel tank temperature sensor
Common causes
- High likelihood: One temperature sensor drifting outside tolerance
- Medium likelihood: Recently active reductant tank heater warming the tank above ambient
Possible symptoms
- Check engine light or NOx warning on
- AdBlue/DEF level or quality warning
- Possible no-start countdown after ignore period
- Failed emissions inspection (NOx)
Diagnostic notes
- The malfunction indicator lamp may illuminate
- This code can affect emissions
Sources
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.