P279F code meaning
Four Wheel Drive (4WD) Range Signal Circuit Low
Powertrain system Generic code P27xx codes Check engine light
What P279F means
P279F means the wired 4WD range signal is below the lowest valid level. Many transfer cases report their range through a resistor-coded switch or a position sensor that produces a defined voltage for each of high, low and neutral; a reading under the lowest of these bands points to a short to ground, a missing sensor supply or a sensor that pulls the line down. No manufacturer documents P279F publicly; GM's 2008 Two-Mode Hybrid data list the circuit code P279D for the same range information, and CARB 13 CCR 1968.2 requires range checks on such inputs. The high-side fault is P27A0, the plausibility fault P279E. Look for chafed harness sections near the transfer case and exhaust and for corroded connectors before replacing the encoder.
P279F at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P279F
- 4WD range indicator dark or flashing
- 4WD low or range changes unavailable
- Warning lamp on
Common causes of P279F
- Most likelyRange signal wire shorted to ground near the transfer case
- PossibleSensor reference voltage missing
- PossibleRange switch or encoder failed with low output
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Four wd range sensorWiring harness
What each part of P279F means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 7 | Area: transmission. |
| 9F | The exact fault in that area. |
What to do next
- Note P279F 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 P279F
What does P279F mean?
P279F means "Four Wheel Drive (4WD) Range Signal Circuit Low". P279F means the wired 4WD range signal is below the lowest valid level. It is a generic code, so it means the same on every make.
Is it safe to drive with P279F?
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 P279F fail an emissions test?
Yes, it can. P279F 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 P279F to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will P279F clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.