P0778

Pressure Control Solenoid B Electrical

Q: Is it safe to drive with P0778?

You can usually limp to a shop, but expect firm or slipping shifts and possibly limp mode. Don't drive long distances until it's fixed.

Q: Can I just clear P0778?

Because this is an electrical fault, it typically returns quickly until the circuit or solenoid is repaired.

Transmission — line pressure control Generic OBD-II Medium

What it means

P0778 means the control module has detected an electrical problem — an open or short — in the circuit for pressure control solenoid B. This solenoid helps regulate the transmission's line pressure, so a fault can produce soft, harsh, or slipping shifts and may put the transmission into limp mode. It affects shifting, not whether the engine will start.

Medium

Can I keep driving? Often driveable but the transmission may limp with soft or harsh shifts — drive gently to a shop; it won't stop the engine from starting.

Real-world scan data

Seen in

149

scans in the past year

Found in

<0.1%

of scans

<0.1%

of scans that found faults

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

Common symptoms

What you'll notice

Harsh, soft, or delayed shifting
Transmission slipping or dropping into limp mode
Reduced acceleration
Check-engine light on

Common causes

Most likely first

Open or short in the pressure control solenoid B circuitLikely
Failed pressure control solenoid BCommon
Damaged wiring or corroded connectorCommon
Loose or corroded electrical connectionsLess often
Failed transmission control module (rare)Less often

How to diagnose & fix

Work through it in order

Read freeze-frame data and note any companion transmission codes.
Inspect the solenoid B wiring and connector for damage, shorts, or corrosion.
Measure the solenoid's resistance and compare with spec — an open or shorted winding sets this electrical code.
Repair wiring faults or replace the solenoid as indicated.
Check transmission fluid level and condition. Clear the code and road-test.

FAQ

Quick answers

Is it safe to drive with P0778?+

You can usually limp to a shop, but expect firm or slipping shifts and possibly limp mode. Don't drive long distances until it's fixed.

Can I just clear P0778?+

Because this is an electrical fault, it typically returns quickly until the circuit or solenoid is repaired.

Read & clear P0778 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX