Timing Reference High Resolution Signal B Phase Not Within Expected Range
The P0379 code means the vehicle's onboard diagnostic system has detected: Timing Reference High Resolution Signal B Phase Not Within Expected Range. This is a critical severity code.
- Keep driving?
- No — stop driving
- DIY difficulty
- hard
- Estimated cost
- $200 - $2,000 (parts and labor)
Best-selling code reader on Amazon. Reads and clears check engine codes on any 1996+ vehicle. Under $30.
Essential for diagnosing sensor codes, checking voltage, and testing circuits. Under $15 and pays for itself on the first job.
Affiliate links — we earn a commission at no extra cost to you.
Common Symptoms
- Check Engine Light on
- Engine timing feels off
- Possible misfires or detonation
- Reduced performance
Probable Causes (Ranked by Likelihood)
- Timing chain jumped one or more teeth Very High
- Worn timing chain stretching beyond tolerance High
- Cam sensor B installed incorrectly Moderate
- Camshaft actuator (VVT) stuck at wrong position Low
Frequently Asked Questions
What does phase not within expected range mean?
The camshaft position relative to the crankshaft is outside the normal window. This indicates the timing is off, typically from a jumped or stretched timing chain.
Can a jumped timing chain cause engine damage?
Yes, on interference engines, a jumped timing chain can cause pistons to hit valves, resulting in bent valves and potential head damage.
How much does timing chain replacement cost?
Timing chain replacement typically costs $800-$2,000 including parts and labor, depending on the engine and vehicle.
Mechanics Guide Step-by-step diagnosis
Step-by-Step Diagnostic Procedure
-
Compare cam-to-crank phase angle on scan tool or oscilloscope against specification.
-
Check timing chain alignment marks.
-
Verify VVT system is not stuck in an advanced or retarded position.
-
If marks are off, inspect timing chain tensioner and guides.
Sources 2
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
- Cross-checked against the SAE J2012:2002 DTC table (2026-08-27)archived scan of the SAE standard — readable copy, not SAE’s current edition
Commonly Affected Vehicles
- 2010-2020 Ford Explorer (3.5L V6)
- 2012-2019 Chevrolet Equinox (2.4L)
- 2008-2018 Honda Accord (2.4L)
- 2011-2020 Toyota Highlander (3.5L V6)
Related Codes
Explore More
Was this helpful?
Send this to whoever is fixing the car — your mechanic, or the person asking what the light means.