P0377 Code: Timing Reference High Resolution Signal B Too Few Pulses
🟠 Moderate severity · drivable
Drivable, but the engine may run roughly or misfire, so have it checked soon.
What P0377 means
The engine computer is seeing fewer timing pulses than expected on the high-resolution timing signal (signal B). Missing pulses usually come from a damaged timing wheel or a failing sensor, which can throw off ignition and fuel timing.
Symptoms
- Check engine light is on
- Rough running or misfire
- Hard starting
- Possible stalling
Common causes
- most common: Damaged timing wheel or reluctor ring with broken teeth
- common: Faulty crankshaft position sensor
- less common: Damaged wiring or loose connector
How to fix it
| Fix | DIY? | Typical cost |
|---|---|---|
| Inspect the timing wheel and reluctor ring for damage | Yes | $0–50 |
| Replace the crankshaft position sensor | Yes | $50–200 |
| Repair damaged sensor wiring | Mechanic | $50–200 |
Frequently asked questions
Can I drive with a P0377 code?
Yes, but the engine may run roughly or misfire, so have it checked soon.
What is the most common cause of P0377?
A damaged timing wheel or reluctor ring with broken teeth, or a failing crank sensor.
How much does it cost to fix a P0377?
Typically $50–$200 for a new crankshaft position sensor.
Related codes
P0335
P0335 Code: Crankshaft Position Sensor Circuit Malfunction
P0375P0375 Code: Timing Reference High Resolution Signal B Malfunction
P0379P0379 Code: Timing Reference High Resolution Signal B No Pulses
Updated 2026-08. This page is informational and not a substitute for professional diagnosis.