P202F — Reductant/Regeneration Supply Control Circuit Range/Performance
The control line that gates the DEF supply pump or the regeneration heating circuit does not respond as commanded — duty cycle, current draw, or response time off-spec.
General code reference. Confirm the definition and diagnostic procedure for your vehicle's year, model and engine. A stored code alone does not identify a failed part.
Affected components
- Reductant supply pump
- Reductant supply relay
Possible causes to check
These are possible checks, not a ranked diagnosis. Follow the vehicle manufacturer's test procedure before replacing parts.
- Supply relay aged or pitted contacts
- Supply pump motor brushes worn
- Sensor element aged beyond calibration window
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
Check each reference's vehicle and model-year scope. General background links do not establish which fault is most likely on your vehicle.
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.