P0378 Code: Timing Reference High Resolution Signal B Intermittent/Erratic
🟠 Moderate severity · drivable
Drivable, but the timing signal drops in and out, which can cause stalling or rough running.
What P0378 means
The high-resolution timing signal (signal B) is cutting in and out or jumping around. Intermittent signals usually come from a loose or corroded connector or damaged wiring, and the problem may come and go.
Symptoms
- Check engine light is on
- Intermittent rough running or misfire
- Random stalling
- Hard starting
Common causes
- most common: Loose or corroded sensor connector
- common: Damaged or chafed wiring
- common: Faulty crankshaft position sensor
- rare: Damaged timing wheel or reluctor ring
How to fix it
| Fix | DIY? | Typical cost |
|---|---|---|
| Clean and tighten the sensor connector | Yes | $0–10 |
| Replace the crankshaft position sensor | Yes | $50–200 |
| Repair damaged or chafed wiring | Mechanic | $50–200 |
Frequently asked questions
Can I drive with a P0378 code?
Yes, but the signal drops in and out, which can cause stalling, so have it fixed soon.
What is the most common cause of P0378?
A loose or corroded sensor connector or damaged wiring, since intermittent codes are usually connection problems.
How much does it cost to fix a P0378?
Cleaning a connector is nearly free; a new sensor is typically $50–$200.
Related codes
P0335
P0335 Code: Crankshaft Position Sensor Circuit Malfunction
P0375P0375 Code: Timing Reference High Resolution Signal B Malfunction
P0389P0389 Code: Crankshaft Position Sensor B Circuit Intermittent
Updated 2026-08. This page is informational and not a substitute for professional diagnosis.