Powertrain, generic (extended)

P263A MIL Control Circuit Low

Check engine lightUsually off
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P263A means the engine module has found the line that switches the malfunction indicator lamp shorted to ground. GM checks it while the low-side driver is off: if the voltage stays low with an impedance to ground of about 0.5 ohm, the lamp control is faulty; the 2014 tables need 50 of 63 samples at 50 ms intervals, the 2019 tables a single sample, with run/crank voltage of at least 11 V and remote start inactive. GM files it as Type B but marks it no MIL, which makes sense because the lamp itself is the affected part; some controllers also log P0650. GM preliminary information PIT5391 lists P263A and P263B among codes left behind when ignition 1 voltage drops out through a KR73 relay or terminal fault on 2014–2016 trucks. A permanently lit lamp is the main symptom.

Likely causes

MIL control wire chafed and touching ground
Loss of ignition 1 voltage via main relay or fuse block terminal
Faulty lamp input in the instrument cluster

Symptoms

  • Engine warning lamp lit permanently
  • Code stored even though the lamp cannot report it reliably

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€40–500
Time0.5–2 h

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

Parts involved

mil lampinstrument clusterwiring harness

Related codes

P263BP0650

References: gsi.ext.gm.com, gsi.ext.gm.com, static.nhtsa.gov.