Powertrain, generic · Transmission

P0804 Upshift/Skip Shift Lamp Control Circuit

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

With GM's skip-shift (CAGS) on manual gearboxes, a '1-4' lamp in the cluster tells the driver that the lockout is active and to shift from 1st directly into 4th. P0804 means the control circuit of this lamp is faulty – open, shorted, or the lamp does not follow its command. No GM table from 2004 to 2025 available to us contains it, because newer cars switch the indicator by a CAN message from the instrument cluster without a separate engine-module line check; the code therefore mainly concerns older vehicles with a lamp driven directly by the engine module. The lockout itself (P0803) keeps working, only the hint is missing; there is no limp mode, and the MIL behavior is not documented.

Likely causes

Bulb or LED in the cluster faulty
Wire or connector between engine module and cluster open or shorted
Instrument cluster board faulty
Engine module output faulty

Symptoms

  • 1-4 lamp never lights or stays on
  • Possibly check engine lamp
  • Lockout works without the hint

Repair estimate

DifficultyEasyDIY possible
Parts and labour€10–300
Time0.3–2 h

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

Parts involved

skip shift lampinstrument clusterengine control module

Related codes

P0803P080CP080DP0650

References: en.wikipedia.org, gsi.ext.gm.com, law.cornell.edu.