What Does P0370 Mean?
The ECM has detected a malfunction in the timing reference high resolution signal A. This signal provides precise crankshaft position data with finer resolution than the standard CKP sensor, used for accurate ignition timing and misfire detection. Loss of this signal affects the ECM's ability to precisely control spark timing and detect individual cylinder misfires. The engine may run rough, misfire, or exhibit reduced performance.
Common Causes
35%
Failed high-resolution timing reference sensor or pickup coil
25%
Damaged or corroded wiring/connector in the timing reference signal A circuit
20%
Damaged high-resolution reluctor wheel (tone ring) with missing or chipped teeth
10%
Excessive sensor-to-reluctor air gap from sensor displacement or ring runout
10%
ECM input circuit fault for the high-resolution timing channel
Diagnostic Steps
1
Check for misfire-related codes alongside this DTC — without the high-resolution timing signal, the ECM cannot perform cylinder-specific misfire detection, which may cause phantom misfire codes or mask real misfires.
2
Verify the timing reference sensor output with an oscilloscope while the engine runs — look for a consistent, clean pulse train with uniform amplitude and spacing; dropouts or missing pulses indicate sensor or reluctor damage.
3
Inspect the timing reference sensor connector for corrosion, oil, or physical damage — the sensor location near the flywheel/flexplate or crank pulley exposes it to harsh conditions.
4
Measure the sensor resistance (for magnetic types) and compare to manufacturer specification — typical values range from 200 to 2,000 ohms depending on the application.
5
Inspect the high-resolution reluctor wheel for physical damage — on many engines this is integral to the flywheel or flexplate and requires removing the transmission inspection cover or bell housing to view.
Estimated Repair Cost
$150 - $700
Parts + labor, varies by vehicle and location
The ECM has detected a malfunction in the timing reference high resolution signal A. This signal provides precise crankshaft position data with finer resolution than the standard CKP sensor, used for accurate ignition timing and misfire detection. Loss of this signal affects the ECM's ability to pre...
The most common cause of P0370 (Timing Reference High Resolution Signal A Malfunction) is: Failed high-resolution timing reference sensor or pickup coil
Typical repair costs for P0370 range from $150 to $700, depending on the vehicle, location, and whether you do it yourself or go to a shop.
The engine can usually continue to run using the standard CKP sensor for basic timing, but precision timing and misfire detection are compromised. Safe to drive short distances but the engine may misfire and run rough. Avoid aggressive driving and have the issue diagnosed promptly.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0370 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Powertrain
System
Ignition System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
