P0766 — Shift Solenoid C Stuck On
Drivable short-term, but fix now to avoid damage.
What P0766 means
This code means shift solenoid C is stuck in the on position, so it keeps directing fluid pressure even when it shouldn't, disrupting normal gear changes. Common causes include a stuck or failed solenoid, debris in the valve body, or low or dirty transmission fluid. Repairs usually involve a fluid service, cleaning or replacing the solenoid, and many cases don't require rebuilding the transmission.
Common symptoms
- Check engine light is on
- Transmission stuck in one gear or shifts erratically
- Harsh or unexpected gear changes
- Car enters limp mode
- Reduced fuel economy
Common causes
- Shift solenoid C stuck on or failed
- Debris or contamination in the valve body
- Low or dirty transmission fluid
- Damaged wiring or short to the solenoid
- Faulty transmission control module
Typical repair cost
$150 – $650
Varies by vehicle and root cause.
Frequently asked questions
Can I keep driving with a P0766 code?
A short trip is usually fine, but don't rely on it. If the transmission holds a gear or drops into limp mode, the car becomes harder to drive safely, so get it diagnosed soon.
How much does it cost to fix a P0766 code?
Repairs generally fall between $150 and $650. A fluid service or cleaning is cheaper, while replacing the solenoid raises the cost depending on your vehicle.
Is a P0766 code serious?
Yes, it deserves prompt attention. A solenoid stuck on disrupts shifting and can stress the transmission, so it's best treated as a high-priority fix.
Why would the solenoid get stuck on?
Debris, varnish from old fluid, or an internal fault can keep the solenoid energized so it won't release. That keeps fluid flowing when it shouldn't and triggers P0766.