P25A6 code meaning
Fuel Mode Select Switch Circuit Low
Powertrain system Generic code P25xx codes Check engine light
What P25A6 means
P25A6 means the fuel mode select switch signal has fallen below the range the module accepts. On a switch that pulls a reference line towards ground when pressed, this is the signature of a signal wire rubbed through to the body or of moisture bridging the switch contacts; a grounded line could otherwise pass for a button held forever. CARB requires input components to be checked for out-of-range values, which is what this code reports. No manufacturer documents P25A6 publicly, though GM's bi-fuel Impala and 2500HD trucks show where the switch lives: dash panel or centre stack, close to cup holders and accessory wiring. Unlike P25A7, the cause is a path to ground, so isolating the switch from its harness is the first test. Fuel selection by hand is lost.
P25A6 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 2 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P25A6
- Fuel mode cannot be changed
- Vehicle remains in one fuel mode
Common causes of P25A6
- Most likelySwitch signal wire chafed to ground behind the dash
- PossibleMoisture or spilt liquid bridging the switch contacts
- Less likelySwitch shorted internally
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Fuel mode switch
What each part of P25A6 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 5 | Area: vehicle speed, idle control and auxiliary inputs. |
| A6 | The exact fault in that area. |
What to do next
- Note P25A6 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 P25A6
What does P25A6 mean?
P25A6 means "Fuel Mode Select Switch Circuit Low". P25A6 means the fuel mode select switch signal has fallen below the range the module accepts. It is a generic code, so it means the same on every make.
Is it safe to drive with P25A6?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P25A6 fail an emissions test?
Yes, it can. P25A6 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P25A6 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P25A6 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.