P0377 — Timing Reference High Resolution Signal B Too Many Pulses
Drive with caution — fix soon.
What P0377 means
This code sets when the engine control module counts more high-resolution timing pulses than it should from the 'B' reference sensor. It's often caused by electrical noise, a damaged or contaminated reluctor ring with extra or distorted teeth, or a faulty sensor or wiring. The fix is usually replacing the sensor, cleaning or replacing the trigger wheel, or repairing wiring, without major engine repairs.
Common symptoms
- Check engine light is on
- Rough or unstable idle
- Engine hesitation or surging
- Hard starting at times
- Reduced engine performance
Common causes
- Electrical noise or interference on the signal circuit
- Damaged or contaminated reluctor ring with extra teeth signals
- Failing crankshaft or camshaft position sensor (B)
- Damaged wiring or poor ground
- Faulty engine control module (rare)
Typical repair cost
$150 – $450
Varies by vehicle and root cause.
Frequently asked questions
Can I keep driving with a P0377 code?
For short trips, usually yes, but don't rely on it long-term. If the engine runs rough or stalls, get it checked promptly to avoid being stranded.
How much does it cost to fix a P0377 code?
Most repairs run between $150 and $450, depending on whether it's a sensor, wiring, or reluctor ring issue.
Is a P0377 code serious?
It's moderately serious. It rarely damages the engine, but the disrupted timing signal can cause poor running, so it's best addressed soon.
What causes 'too many pulses' in a P0377 code?
Usually electrical noise or a contaminated or damaged trigger wheel makes the sensor read extra pulses, so the computer counts more than the engine actually produces.