Powertrain, generic (extended)

P226B Turbocharger/Supercharger A Boost Pressure Too High - Mechanical

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

P226B reports boost from turbocharger or supercharger A rising too high for a mechanical reason, for instance a wastegate or bypass that will not open or a seized actuator linkage, rather than a sensor or wiring fault. VW's 2014 book for the supercharged Touareg 3.0 TSI sets it when boost passes 250 kPa. GM uses the code only for European calibrations: its 2018 diesel tables list P226B as an EOBD code in the boost-system fault groups, while the US software maps the same fault group to P2263. CARB requires boosted engines to detect overboost. Where P0234 judges a deviation above the target, P226B points to a mechanical cause; P2262 describes boost that does not appear at all. To protect the engine the ECM usually reduces torque, and some engines open a relief path.

Likely causes

Wastegate flap seized closed by corrosion or carbon
Seized or misadjusted wastegate or VGT actuator linkage
Vacuum or pressure line to a pneumatic actuator leaking or blocked
Supercharger bypass valve not opening

Symptoms

  • Sudden power cut or reduced-power mode under load
  • MIL on
  • Unusually strong surge of power just before the cut

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

turbochargerwastegatewastegate actuator

Related codes

P0234P2262P2263P0299P0243

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