Quick answer: The P0375 code indicates a malfunction in the engine’s high-resolution timing reference signal ‘B’. This code affects the ignition and fuel injection timing systems controlled by the PCM. It is a high-urgency issue that frequently causes engine hesitation, stalling, or a complete no-start condition.
If your Check Engine Light is illuminated and your scan tool displays code P0375, your engine computer has lost a critical timing signal. Driving with this fault can lead to sudden loss of power or unexpected stalling. Below, we break down what this code means, what causes it, how to troubleshoot it, and expected repair costs.
What Does P0375 Mean?
Code P0375 stands for “Timing Reference High Resolution Signal B Malfunction.” The Powertrain Control Module (PCM) uses high-resolution timing sensors-often mounted near the crankshaft, camshaft, or inside an optical distributor-to measure engine speed and position down to fractions of a degree. These sensors generate multiple signal channels to time spark plug firing and fuel injector pulses precisely. Signal ‘B’ represents a specific high-frequency pulse track. When the PCM detects missing, noisy, or erratic pulses on the Signal B circuit, it sets code P0375 and enters a failsafe mode, disrupting smooth engine operation.
Symptoms
- Illuminated Check Engine Light on the instrument panel
- Engine hesitation, jerking, or stumbling under load
- Frequent engine stalling while idling or stopping
- Hard starting or an engine that cranks but will not start
- Severe engine misfires and erratic RPM tachometer movement
- Noticeable drop in engine power and fuel efficiency
Possible Causes
Before buying expensive replacement parts, remember that simple wiring faults or dirty electrical connectors cause this trouble code far more often than a complete computer failure.
- Corroded, loose, or oil-soaked sensor wiring harness connectors
- Damaged, melted, or broken signal wires in the timing sensor circuit
- Faulty high-resolution timing reference sensor (crankshaft, camshaft, or optical unit)
- Low battery voltage or bad ground connections during engine cranking
- Internal mechanical failure of the sensor pulse wheel or optical disc
- Failed Powertrain Control Module (PCM), though actual computer failure is rare
Check These Yourself Before Visiting a Mechanic
- Inspect the sensor connector: Locate the timing or position sensor, disconnect its plug, and check for bent pins, green corrosion, or engine oil buildup. Clean the contacts thoroughly with electrical contact spray.
- Check the wiring harness: Trace the wire harness leading away from the timing sensor. Look for burned insulation from exhaust heat, sharp bends, or places where the wire rubs against engine brackets.
- Test battery condition: Ensure your battery voltage reads at least 12.6 volts with the key off. Voltage drops during cranking can distort delicate optical or magnetic timing signals.
How to Fix It
- Perform a visual inspection of all relevant wiring and harness connectors, repairing damaged wires and securing loose connections.
- Clear the diagnostic trouble code with an OBD-II scanner and perform a test drive to verify if the code returns instantly.
- Test battery health, terminal tightness, and main engine grounds to rule out system voltage drops.
- Measure reference voltage, ground, and output signal frequency at the timing sensor connector using a digital multimeter or oscilloscope.
- Replace the faulty high-resolution timing sensor, crankshaft/camshaft sensor, or distributor assembly if signal output is distorted or absent.
- Verify PCM pin signal integrity and update or replace the control module if all external circuits and sensors test within specification.
Estimated Repair Costs (2026)
| Job | Parts ($) | Labor ($) |
|---|---|---|
| Diagnostic Inspection | $0 | $100 – $150 |
| Wiring & Connector Repair | $10 – $35 | $100 – $200 |
| Timing / Position Sensor Replacement | $45 – $160 | $90 – $220 |
| Distributor Assembly Replacement (if applicable) | $140 – $380 | $120 – $280 |
| PCM Replacement & Programming | $450 – $950 | $180 – $350 |
Note: these are 2026 estimates in US dollars; costs vary by make and model.
Frequently Asked Questions
Can I drive with the P0375 code?
No, you should avoid driving with a P0375 code. Because the PCM depends on Signal B for precise ignition and fuel timing, the engine may stall unexpectedly in traffic or fail to start once turned off.
How do I clear the P0375 code?
You can reset the code using a standard OBD-II scanner plugged into the diagnostic port under your dash. However, if the underlying circuit or sensor fault is not repaired, the code will retrigger almost immediately after starting the engine.
What is the difference between Timing Signal A and Signal B?
Signal A typically provides a lower-resolution pulse track used by the PCM for basic engine speed calculation, while Signal B provides a high-resolution, fine-detail pulse track required for precise spark advanced and fuel metering timing.