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.

Medium severity. Can I keep driving?You can normally drive in moderation, but get it repaired soon: if the valve is stuck open, the engine may idle very poorly.

Bank 2 is the side without cylinder 1, so it only exists on V or boxer engines.

Symptoms

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

Most likely causes

Blocked, leaking or kinked vacuum line to the bank 2 actuator
Bypass flap of bank 2 sticking from soot deposits
Faulty actuator or control solenoid

What to check, in order

Start with the simplest. You can tick off each step.

Check the connector and any vacuum hoses
Use the scanner to command the movement and compare the actual position with the requested one.
Use live data to compare the commanded opening with the actual opening
Clean the valve and passages if they are clogged with carbon
Test the actuator with the scanner
Replace the valve if it still does not follow the command after cleaning

Good to know

Repair difficulty: medium
It affects emissions.

What each character of P26FC means

P: Powertrain: engine and transmission
2: Generic code: same on every make
6: Control modules and outputs
FC: Specific fault in that system

Frequently asked questions

Can I keep driving with code P26FC?

You can normally drive in moderation, but get it repaired soon: if the valve is stuck open, the engine may idle very poorly.

What causes code P26FC?

The most common causes are: blocked, leaking or kinked vacuum line to the bank 2 actuator; bypass flap of bank 2 sticking from soot deposits; faulty actuator or control solenoid.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.