P27A0
Four Wheel Drive (4WD) Range Signal Circuit High
Transmission / transfer case
Generic OBD-II
Low
What it means
P27A0 means the controller sees an abnormally high voltage on the four-wheel-drive range signal circuit — the input that tells it whether the transfer case is in high or low range. It usually points to a short to voltage, an open, or a failed range sensor. Everyday driving is fine; the concern is reliable 4WD low-range engagement.
Low
Can I keep driving? Yes — normal 2WD/AWD driving is unaffected; you may just be unable to select or confirm 4WD low range until it's fixed.
Common symptoms
What you'll notice
- Check-engine or service-4WD warning light on
- Unable to shift into or out of 4WD low range
- 4WD range display reads incorrectly or goes blank
- Transfer case stays in its current range
Common causes
Most likely first
- Short to voltage or open in the 4WD range sensor/switch circuitLikely
- Faulty 4WD range position sensor or selector switchCommon
- Transfer case shift motor or encoder faultCommon
- Damaged or corroded connector/wiring at the transfer caseLess often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and inspect the transfer case range sensor connector and wiring.
- Check the range signal voltage against spec through its range positions.
- Test the transfer case encoder/shift motor operation.
- Repair the wiring or replace the range sensor/switch, then clear and retest.
FAQ
Quick answers
Is it safe to drive with P27A0?+
Yes for normal road driving. The fault affects the 4WD range signal, so the main risk is not being able to engage low range for off-road or towing use.
Can I just clear P27A0?+
It returns until the range circuit or sensor is repaired, since the controller keeps reading the range signal.
Related codes
Often seen with P27A0
Read & clear P27A0 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX