Powertrain, generic (extended)

P20F6 Reductant Injection Valve Stuck Open (Bank 1 Unit 1)

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

Between pulses the dosing valve must seal tightly so DEF only enters the exhaust when commanded. P20F6 means the control unit concluded that the first valve on bank 1 stays open: the pressure collapses, or the pump has to work much harder to hold it than the commanded quantity explains. A Cummins patent describes this kind of check, comparing the measured pump effort with the expected flow; a strongly negative error points to a stuck-open valve, a leak or a disconnected line. FCA lists P20F6 for the Jeep Compass with the 2.0 L diesel (sales code EBS) in bulletins 18-034-20, 18-008-23 and 18-026-23 and cures it with control unit software; one case comes with system and DCU supply voltage too high. Overdosing risks ammonia slip and deposits. The stuck-closed counterpart is P208E, bank 2 is P20F7.

Likely causes

Crystals or debris on the valve seat keeping the valve from closing
Mechanically sticking or heat-damaged dosing valve
Control unit software misjudging valve closure, cured by an update
Leaking or detached line at the valve imitating an open valve

Symptoms

  • Check engine light and DEF warning
  • Higher DEF consumption, white deposits in the exhaust or ammonia smell
  • Dosing switched off and later inducement

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€0–900
Time0.3–2.5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

reductant injection valve

Related codes

P20F7P208EP2047P202EP20F5

References: static.nhtsa.gov, static.nhtsa.gov, patents.google.com, law.cornell.edu.