P0804 code meaning
Upshift/Skip Shift Lamp Control Circuit
What P0804 means
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.
P0804 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyEasy, DIY possible
- Typical labor0.3 to 2 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0804
- 1-4 lamp never lights or stays on
- Possibly check engine lamp
- Lockout works without the hint
Common causes of P0804
- Most likelyBulb or LED in the cluster faulty
- PossibleWire or connector between engine module and cluster open or shorted
- PossibleInstrument cluster board faulty
- Less likelyEngine module output faulty
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Skip shift lampInstrument clusterEngine control module
What each part of P0804 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 8 | Area: transmission. |
| 04 | The exact fault in that area. |
What to do next
- Note P0804 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0804
What does P0804 mean?
P0804 means "Upshift/Skip Shift Lamp Control Circuit". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with P0804?
P0804 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will P0804 fail an emissions test?
P0804 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is P0804 to fix?
Difficulty: easy. A typical repair takes 0.3 to 2 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P0804 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.