P0379
Timing Reference High Resolution Signal B No Pulses
Timing reference / crank position
Generic OBD-II
High
What it means
P0379 means the ECM is receiving no pulses on the high-resolution timing-reference "B" circuit. This signal gives the ECM a precise crankshaft timing reference for spark and fuel. With no pulses at all, the engine can misfire badly, stall, or fail to start, since the ECM has lost part of its timing information.
High
Can I keep driving? Often a no-start or stall — without this timing signal the ECM loses its high-resolution crank reference, so the engine may not run at all; have it towed rather than driven.
Common symptoms
What you'll notice
- No-start or stalling
- Hard starting
- Check-engine light on
- Rough running or misfire
Common causes
Most likely first
- Faulty crankshaft position sensor (high-resolution signal source)Likely
- Open circuit in the signal wiring (no pulses reaching the ECM)Common
- Damaged reluctor / tone ringCommon
- Loose or corroded connectorLess often
- Faulty ECM (rare)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and check whether the signal is fully absent.
- Test the sensor's signal and power/ground circuits for an open.
- Inspect the reluctor ring for damage or debris.
- Check the connector for corrosion or backed-out pins.
- Replace the sensor if it produces no signal; evaluate the ECM last. Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P0379?+
If it's causing a no-start or stall, no — have it towed. Losing the timing reference while driving can leave you stranded.
Can I just clear P0379?+
It won't stay cleared while the signal is missing; the sensor or wiring must be repaired first.
Related codes
Often seen with P0379
Read & clear P0379 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX