P20E7
Reductant Injection Air Pressure Too High
The DEF system air-assist pressure exceeds the upper threshold — pressure-control valve stuck closed or air pump runaway.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
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)
Common causes
Ordered by how often each turns out to be the cause.
- Pressure control valve stuck closedCommon
- Air pump does not regulatePossible
Parts involved
- Reductant Air Pump
- Reductant Air Pressure Control Valve
P20E7 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.