Powertrain, generic (extended)

P205F Reductant System Performance (Bank 2)

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

P205F is the Bank 2 version of the reductant system performance check, meant for engines in which the second cylinder bank has its own SCR branch with separate pressure supply or valve. It applies when that branch is electrically sound but fails to reach or regulate the pressure or quantity the controller asks for. No manufacturer publicly documents P205F; even a V-engine such as Ram's 3.0 L EcoDiesel V6 lists delivery problems as P204F in its bulletins. The Bank 1 logic gives orientation: GM's 6.6 L LML waits for 30 failed build-up attempts below 350 kPa before setting a Type A code. CARB requires every SCR system to detect delivery faults before emissions exceed the limits. Look for blocked lines, a sticking valve or crystallised DEF in the second branch.

Likely causes

Blocked or frozen DEF line to the Bank 2 branch
Bank 2 injector sticking due to DEF crystals
Insufficient pump or metering unit pressure for the second branch

Symptoms

  • MIL and DEF warning on
  • Higher NOx from Bank 2, possible inducement

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–2,500
Time1–6 h

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

Parts involved

reductant pumpreductant metering unitreductant linesreductant injection valve

Related codes

P204FP20E8P20E9P201A

References: law.cornell.edu, gsi.ext.gm.com, static.nhtsa.gov.