P26FC EGR Cooler Bypass Control Stuck Closed (Bank 2)

P26FC is the bank 2 version of P26FB and only exists on engines with a separate EGR cooler and bypass for each cylinder bank, typically V-configuration diesels. The engine module has commanded the bypass of the second bank open, but position feedback or the resulting gas temperature shows it is still closed, so the exhaust gas keeps flowing through the cooler during warm-up. No manufacturer documents P26FC in public. For bank 1, FCA's STAR case S2018000001 on the 3.0 L EcoDiesel shows how such a fault arises: a clogged orifice in the vacuum line to the actuator, or a flap that does not move freely. CARB requires the EGR cooler bypass to be checked for proper response while cold-start emission strategies are active. If P26FB and P26FC appear together, a shared vacuum supply or solenoid is the likely cause.

Likely causes

Symptoms

• Check engine light on
• Slower warm-up of the exhaust aftertreatment

Repair estimate

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

Parts involved

Related codes

References: law.cornell.edu, static.nhtsa.gov.