Quick answer: The P0374 code indicates that the engine control module is receiving no pulses from the high-resolution timing reference signal ‘A’. This affects the ignition and fuel delivery systems, making it a critical issue that usually results in engine stalling, severe misfires, or a complete no-start condition.
Seeing a check engine light accompanied by a sudden engine stall or failure to start can be alarming. Trouble code P0374 points directly to a missing high-resolution timing signal that your engine’s computer relies on for precise fuel injection and spark delivery. In this guide, you will learn what causes this signal loss, how to recognize the symptoms, and the proper steps to fix it.
What Does P0374 Mean?
The powertrain control module (PCM) relies on timing reference signals to determine the exact position and speed of the engine crankshaft or optical distributor shaft. While standard timing signals provide a few pulses per engine revolution, a high-resolution signal provides dozens or hundreds of fine pulse counts. This high level of detail allows the PCM to make instantaneous adjustments to ignition timing and fuel injector timing.
When the P0374 code is stored, the PCM has detected zero high-resolution pulses from signal circuit ‘A’ while the engine was turning. Without these continuous pulses, the engine computer loses its precise synchronization point and cannot properly command the injectors or ignition coils, leading to severe performance issues or an immediate engine shutdown.
Symptoms
- Engine cranks normally but fails to start
- Sudden engine stalling while idling or driving
- Severe engine hesitation, sputtering, or misfiring
- Illuminated Check Engine Light (Service Engine Soon)
- Intermittent loss of power during acceleration
Possible Causes
The most common mistake when diagnosing P0374 is replacing expensive sensors or control modules before checking basic wiring connections.
- Corroded, loose, or damaged wiring harness connectors at the timing sensor
- Frayed, broken, or shorted high-resolution signal wires
- Faulty crankshaft position, camshaft position, or optical distributor sensor
- Damaged sensor tone ring or dirty optical encoder wheel
- Failed or failing powertrain control module (PCM)
Check These Yourself Before Visiting a Mechanic
- Inspect the sensor connector: Unplug the timing sensor connector and look for bent pins, moisture, or green corrosion inside the housing.
- Examine visible wiring: Trace the sensor wiring harness back toward the engine block to check for burnt insulation, rubbing against belts, or melted wires near exhaust components.
- Check system voltage: Use a digital multimeter to confirm your vehicle’s battery voltage is healthy (above 12.4V with the engine off), as low system voltage can cause electronic control signal dropouts.
How to Fix It
- Connect an OBD-II scanner to read freeze-frame data and check for related timing sensor or misfire codes.
- Perform a thorough visual inspection of the timing sensor, connector, and associated wiring. Repair any visibly broken wires or dirty contacts.
- Verify reference voltage (typically 5V or 12V) and ground at the sensor connector using a multimeter while the key is in the ON position.
- Test the high-resolution signal output with an oscilloscope or graphic multimeter while cranking the engine to confirm whether the sensor is creating a clean pulse wave.
- Replace the faulty position or optical timing sensor if input voltage is present but no output pulses are generated.
- Repair damaged circuit wiring between the sensor and PCM, or replace and reprogram the PCM if sensor output is verified good but signal fails to reach the module.
Estimated Repair Costs (2026)
| Job | Parts ($) | Labor ($) |
|---|---|---|
| Wiring Harness Repair / Cleaning | $10 – $40 | $100 – $200 |
| Crankshaft / Optical Position Sensor | $60 – $200 | $120 – $250 |
| Distributor / Tone Ring Replacement | $150 – $450 | $150 – $350 |
| PCM Replacement & Programming | $350 – $850 | $150 – $300 |
Note: These estimates reflect projected 2026 prices in US dollars. Total repair costs vary depending on vehicle make, engine layout, and local shop labor rates.
Frequently Asked Questions
Can I drive with the P0374 code?
No, driving with a active P0374 code is generally impossible or unsafe. Loss of the high-resolution timing signal usually causes the engine to stall unexpectedly or prevents it from starting at all, leaving you stranded.
How do I clear the P0374 code?
You can clear the code using any standard OBD-II scanner after making the necessary repairs. However, if the missing signal fault is still present, the engine control module will immediately trigger the code again upon cranking.
What causes a high-resolution signal to fail intermittently?
Intermittent signal failure is often triggered by thermal expansion inside an aging sensor, engine vibration loosening a poor pin fitment at the electrical plug, or poor ground connections causing electronic noise on the signal wire.