P2668 code meaning
Fuel Mode Indicator Lamp Control Circuit
What P2668 means
Bi-fuel vehicles tell the driver which fuel is in use through a small indicator, often built into the fuel selector button. On GM's 2016 Silverado and Sierra with CNG the light is off on gasoline, steady on natural gas, flashes once per second during a changeover and flashes about ten times per second when the CNG system has a fault; the 2015 Impala Bi-Fuel uses a similar light in its CNG switch. P2668 indicates that the module driving this lamp has found a fault in its control circuit, such as an open wire or a failed bulb or LED. No manufacturer documents the code publicly. Fuel switching itself is unaffected, but the driver loses the fuel mode display and the error warning. P26E2 and P26E3 are the low and high variants.
P2668 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyEasy, DIY possible
- Typical labor0.3 to 1.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P2668
- Fuel mode lamp stays dark in gas mode
- No flashing during fuel changeover or on errors
Common causes of P2668
- Most likelyIndicator LED or bulb in the selector switch failed
- PossibleOpen wire or loose connector at the switch
- Less likelyLamp driver in the control module defective
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Fuel mode lampInstrument clusterWiring harness
What each part of P2668 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 6 | Area: computer (engine control module) and output circuits. |
| 68 | The exact fault in that area. |
What to do next
- Note P2668 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 P2668
What does P2668 mean?
P2668 means "Fuel Mode Indicator Lamp Control Circuit". Bi-fuel vehicles tell the driver which fuel is in use through a small indicator, often built into the fuel selector button. It is a generic code, so it means the same on every make.
Is it safe to drive with P2668?
P2668 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will P2668 fail an emissions test?
P2668 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 P2668 to fix?
Difficulty: easy. A typical repair takes 0.3 to 1.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P2668 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.