P0800
Transfer Case Control System (MIL Request)
Transmission / transfer case
Generic OBD-II
Medium
What it means
P0800 means the transfer case control module has requested the check-engine light because it detected a fault in the four-wheel-drive transfer case system. The engine and normal driving aren't affected, but 4WD may not engage or disengage as it should. Because this code is a request flag, the real fault is usually stored as a separate transfer-case code — read that module to pinpoint it.
Medium
Can I keep driving? Normal on-road driving is usually fine, but four-wheel-drive may not engage or disengage correctly — avoid relying on 4WD until it's diagnosed.
Common symptoms
What you'll notice
- Check-engine light on
- Four-wheel-drive won't engage or disengage properly
- 4WD/AWD warning light on the dash
- Transfer case stuck in one range (high or low)
- Grinding or binding when turning in 4WD
Common causes
Most likely first
- Fault in the transfer case control module requesting the MILLikely
- Malfunctioning transfer case shift motor or actuatorCommon
- Failed transfer case mode/range selector switchCommon
- Damaged wiring or connectors in the transfer case circuitLess often
- Low or contaminated transfer case fluidLess often
How to diagnose & fix
Work through it in order
- Scan the transfer case control module for its own stored codes — P0800 is a request flag, so the real fault is usually a companion code.
- Inspect the transfer case wiring, connectors, and the shift motor for damage or corrosion.
- Check the mode/range selector switch operation.
- Check transfer case fluid level and condition.
- Test the shift motor and control module; replace the faulty component identified.
FAQ
Quick answers
Is it safe to drive with P0800?+
For normal two-wheel-drive road use, usually yes. But the four-wheel-drive system may not work when you need it, so don't count on 4WD off-road or in bad weather until it's fixed.
Can I just clear P0800?+
It returns until the underlying transfer case fault is repaired. Because P0800 is a MIL request, always read the transfer case module for the specific code driving it.
Related codes
Often seen with P0800
Read & clear P0800 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