P0370
Timing Reference High Resolution Signal A Malfunction
If your vehicle's onboard computer has flagged the diagnostic trouble code P0370, it refers to a detected anomaly regarding "Timing Reference High Resolution Signal A Malfunction". This systemic engine fault needs a targeted check before symptoms expand.
Driver's Summary
Storing code P0370 is your car's way of telling you something is wrong with the timing reference high resolution signal a malfunction. Drivers typically experience hard start, misfire, lack of power, check engine light when this code is active. Given the high severity of this code, continuing to drive risks significant mechanical damage. Have it diagnosed immediately.
Symptoms
Hard start, misfire, lack of power, check engine light
Common Causes
- Defective optical/hall effect sensor in distributor or injection pump
- Damaged reluctor wheel
- Corroded wiring harness
- PCM failure
How to Fix
- 1 Replace optical/crank sensor
- 2 Replace reluctor wheel
- 3 Repair wiring
- 4 Replace PCM
Technical Explanation
Detection of P0370 occurs when the ECM cross-references multiple sensor inputs and determines that the reported values are physically inconsistent or out-of-range. 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. The MIL illuminates after the fault is confirmed on two consecutive drive cycles, and the freeze frame data captured at first detection is stored in the PCM's memory for diagnostic reference.
Is It Safe to Drive?
With P0370 active, your engine or transmission is not operating within design parameters. Short-term driving may seem fine, but internal damage is accumulating — particularly to defective optical/hall effect sensor in distributor or injection pump.
Mechanic's Pro Tip
Before replacing any component on P0370, 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.
Sensor replacement: 150 - 400