Powertrain, generic (extended)

P2AA6 EGR Cooler Bypass Control Circuit Driver Current/Temperature Too High Bank 2

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P2AA6 is the bank 2 version of the bypass driver protection code. It only exists on engines with a separate EGR cooler and bypass actuator for the second cylinder bank, typically V engines whose banks each have their own exhaust manifold feeding EGR. The output stage for that actuator reports excessive current or junction heat and shuts itself off, which leaves the flap where it was. No manufacturer documents P2AA6 publicly. GM's diesel tables, which define the bank 1 code P2AA5 with a 170 °C driver limit and a Type B rating, show no bank 2 counterpart, as those engines use a single bypass. Causes match bank 1: a binding flap, a damaged motor or a partial short. Circuit faults on bank 2 are P248E, P2490 and P2491; a stuck flap is P24A6.

Likely causes

Bank 2 bypass flap binding on soot or corrosion
Internal fault in the bank 2 actuator motor
Partial short in the bank 2 actuator wiring
Faulty driver stage in the engine control module

Symptoms

  • Malfunction indicator lamp on
  • Bank 2 bypass flap stays in its last position
  • Possible NOx or EGR temperature codes for bank 2

Repair estimate

DifficultyHardWorkshop job
Parts and labour€150–1,200
Time1–4 h

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

Parts involved

egr cooler bypass valve b2ecm

Related codes

P2AA5P248EP2490P2491P24A6

References: law.cornell.edu, gsi.ext.gm.com.