Powertrain, generic (extended)

P26E6 Starter Relay B Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P26E6 reports a short to positive on the control line of starter relay B. GM tests for it while its driver for the tandem starter pinion relay is off: if the line still shows 0.5 Ohm or less toward a power source for 40 out of 50 checks taken every 50 ms, with the engine stopped and at least 11 V available, the code is stored as type B. The danger of this fault is a relay that is energised without a command, so the pinion could be pushed into the ring gear. The diagnostic appears in GM's 2018 and 2023 tables with the same thresholds. P26E4 and P26E5 cover open and grounded circuits.

Likely causes

Relay B control wire shorted to a battery-powered wire, e.g. under the battery tray
Relay B internally fed or contacts welded
Engine module driver output not switching off

Symptoms

  • Check engine light
  • Stop-start disabled
  • Starter noise or grinding without a start command

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–800
Time0.5–3 h

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

Parts involved

starter relay bwiring harness

Related codes

P26E4P26E5P0617P26F2

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