P0379
Timing Reference High Resolution Signal B No Pulses
Encountering the engine check light code P0379 signifies an explicit mechanical or electrical operational breakdown categorized as "Timing Reference High Resolution Signal B No Pulses". Professional scanner tools usually flag this subsystem loop early on.
Driver's Summary
Your vehicle's computer logged P0379 after detecting a malfunction in the timing reference high resolution signal b no pulses system. You may notice engine cranks but won't start, all of which are direct consequences of this malfunction. This is a serious fault — avoid extended driving and have your vehicle inspected by a mechanic as soon as possible to prevent further damage.
Symptoms
Engine cranks but won't start
Common Causes
- Dead sensor B
- Unplugged harness
- Broken wire in the circuit
- PCM fault
How to Fix
- 1 Replace sensor B
- 2 Reconnect wiring harness
- 3 Repair broken circuit
- 4 Diagnose PCM
Technical Explanation
To set P0379, the PCM samples the affected circuit multiple times per second, comparing live readings against manufacturer-programmed operating windows. Misfire rate is counted per cylinder over rolling windows and compared against two thresholds: a catalyst-damaging rate (triggers flashing MIL) and an emissions-exceeding rate (triggers solid MIL). The PCM logs which cylinder is misfiring based on crankshaft position at the time of each detected event. Once confirmed, the code is stored as a permanent DTC and the MIL is activated. The freeze frame snapshot — recording RPM, load, coolant temperature, and fuel trim at fault detection — is also saved and is critical for accurate diagnosis.
Is It Safe to Drive?
With P0379 active, your engine or transmission is not operating within design parameters. Short-term driving may seem fine, but internal damage is accumulating — particularly to dead sensor b.
Mechanic's Pro Tip
Before replacing any component on P0379, spend 5 minutes inspecting the wiring harness and connector first — corrosion, chafed insulation, and backed-out pins cause the majority of these faults and cost nothing to fix. Use a multimeter to measure voltage drop across the connector pins under load; anything above 0.1V indicates excessive resistance that will cause intermittent failures even after replacing the sensor.
Related Fault Codes
Frequently Asked Questions
What does OBD2 code P0379 mean?
OBD2 code P0379 refers to Timing Reference High Resolution Signal B No Pulses. Encountering the engine check light code P0379 signifies an explicit mechanical or electrical operational breakdown categorized as "Timing Reference High Resolution Signal B No Pulses". Professional scanner tools usually flag this subsystem loop early on.
What are the most common symptoms of DTC P0379?
Drivers experiencing code P0379 typically report: Engine cranks but won't start.
Is it safe to drive with trouble code P0379 active?
With P0379 active, your engine or transmission is not operating within design parameters. Short-term driving may seem fine, but internal damage is accumulating — particularly to dead sensor b.
How much does it cost to fix code P0379?
The estimated repair cost for P0379 ranges from $100 to $450 USD. Sensor replacement: 150 - 400
Sensor replacement: 150 - 400
Need Professional Diagnostic Assistance?
Always verify sensor signals and wiring integrity with an OBD2 scanner before purchasing replacement parts.
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