Powertrain, generic (extended)

P26FB EGR Cooler Bypass Control Stuck Closed (Bank 1)

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

A diesel engine routes recirculated exhaust around the EGR cooler while it is cold, so that the gas warms the engine and aftertreatment; later the bypass flap closes and the gas passes through the cooler. P26FB means the bypass on bank 1 does not open when commanded and stays in the closed, cooling position. FCA uses the code on the 3.0 L EcoDiesel (Ram 1500 2020, Jeep Wrangler). STAR case S2018000001 links it to a 0.6 mm brass restrictor that clogs inside the vacuum line running from the remote solenoid to the flap actuator; the tube must be replaced rather than cleaned, and the actuator is checked by hand for sticking. FCA's PCM software bulletins 18-008-21 and 18-002-23 list P26FB among the codes they address. CARB lists the bypass among parts that must respond during cold-start strategies, so warm-up emissions rise.

Likely causes

Blocked orifice or kinked vacuum line to the bypass actuator
Bypass flap sticking from soot and deposits
Faulty vacuum solenoid or weak vacuum supply
Outdated PCM calibration with too sensitive detection

Symptoms

  • Check engine light on
  • Longer warm-up of engine and exhaust aftertreatment
  • Usually no noticeable change in driveability

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–1,500
Time0.5–4 h

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

Parts involved

egr cooler bypass valve b1bypass actuator

Related codes

P26FCP2493P24C4P2457

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