What does it mean?
P1220 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Excessive Cycling of Reductant Line Air Purging Control .
Symptoms
- Check engine lamp on, usually with reductant system messages in the instrument cluster
- Warning of a countdown to speed restriction or a refusal to restart the engine
- Power reduction or derate once the counter expires
- White crystalline deposits around the dosing injector, lines or tank cap
- Audible pump or valve clicking far more often than normal
- Higher reductant consumption than expected
Likely causes
- Leak in the reductant line, its fittings or the dosing injector, so pressure will not hold after purging
- Crystallised urea deposits in the dosing injector, the line or the nozzle
- Faulty or stuck air purge valve
- Reductant pump or its pressure sensor unable to build and hold the target pressure
- Poor quality or contaminated reductant fluid, or the wrong fluid in the tank
- Wiring or connector fault at the purge valve, letting it cycle uncontrolled
- Outdated aftertreatment control software
How to fix it
- Read all aftertreatment codes together, since one hardware fault usually sets several
- Inspect the reductant lines, fittings and dosing injector for leaks, wet marks and white crystals
- Check reductant quality and level, and confirm the correct fluid has been used
- Watch reductant pressure on the scan tool during a purge cycle to see whether it holds
- Command the purge valve with the scan tool and listen and feel for correct operation
- Check the valve wiring, connector and ground before replacing it
- Clean or renew a crystallised dosing injector and heated line, then run a system test to confirm the cycling has stopped
- Check for updated aftertreatment software before replacing major components