OBD-II Code P0375 — What It Means & How to Fix It

What Does This Error Mean?

P0375 means the PCM detected a malfunction in the high-resolution timing reference signal B. This is a secondary high-precision timing signal — the B designation indicates a second sensor of this type on the engine. A fault here causes the PCM to lose precise timing data, leading to inaccurate fuel injection and ignition timing. Expect hesitation, rough running, misfires, and reduced performance.

Affected Models

Older GM vehicles — primarily late 1990s through mid-2000s trucks and performance cars
Common in GM LS-series engines with dual high-resolution timing inputs
Some Ford and Chrysler performance platforms with secondary timing reference sensors
Less common on modern vehicles where standard CKP and CMP sensors cover all timing needs
More likely on vehicles with complex or high-performance ignition management systems

Common Causes

Failed high-resolution timing sensor B producing no output or an invalid signal
Damaged or broken wiring in the timing reference B sensor circuit
Corroded or loose connector at the high-resolution timing sensor B
Damaged tone wheel or debris on the reluctor ring for sensor B
Incorrect air gap between sensor B and its corresponding tone wheel

How to Fix It

Identify the location of high-resolution timing sensor B on your specific vehicle. On GM vehicles it may be mounted near the crankshaft or within the distributor assembly. The B designation means it is the second of two such sensors. Your factory service manual is essential here.

Without the service manual for your exact vehicle, finding this sensor is very difficult. P0375 is uncommon enough that generic repair sites may not have vehicle-specific location information.
Inspect the sensor connector and wiring for corrosion, damage, or a loose connection. On older vehicles, these connections are often in high-heat, high-vibration areas. Clean the connector with electrical contact cleaner and reseat firmly.

Wiggle the connector and harness while the engine is running. An intermittent connection will often cause a momentary idle change or scanner signal dropout.
Check the air gap between sensor B and its tone wheel. The gap must be within manufacturer specification — usually 0.5 to 1.5 mm. Use a feeler gauge to measure and adjust the sensor position if the gap is too large or too small.

A gap that is slightly too large will cause a weak signal that the PCM cannot reliably read. This can produce an intermittent or a steady malfunction code depending on how much the gap is off.
Inspect the tone wheel that sensor B reads from. Look for missing, chipped, or broken teeth. Clean any debris or metal particles from the wheel surface. A damaged tooth will cause a consistent signal fault at the same point in every engine revolution.

Use a bright light and inspect every tooth. Run your fingertip around the wheel to feel for irregularities that might not be immediately visible.
Replace the high-resolution timing sensor B if the tone wheel and wiring are in good condition. Set the air gap to specification during installation. Clear all codes and test drive. Confirm no timing reference codes return over several drive cycles.

If P0375 returns after sensor replacement and gap adjustment, a lab scope diagnosis is needed to see the actual signal waveform and identify whether the issue is mechanical or electrical.

When to Call a Professional

Locating the high-resolution timing sensor B requires manufacturer-specific service documentation. If the sensor and wiring are in good shape but the code persists, a technician with a lab scope can view the actual signal waveform and identify the fault. Diagnosis runs $80-$150. Sensor replacement parts typically cost $30-$100.

Frequently Asked Questions

What is the difference between signal A and signal B in P0370 vs. P0375?

Signal A refers to the first high-resolution timing sensor on the engine. Signal B refers to a second high-resolution timing sensor — found on some engine designs with dual high-resolution reference inputs. Both serve the same purpose of providing precise engine position data. Not all vehicles have a signal B sensor — it depends on the engine management design.

Is P0375 common on modern vehicles?

No. Modern engine management systems handle all timing calculations from the standard crankshaft and camshaft position sensors. The separate high-resolution timing sensor system was used primarily in certain GM engine families from the late 1990s and early 2000s. If you have a vehicle newer than around 2010 and see P0375, verify the code carefully.

Will P0375 cause a no-start?

It can on vehicles where the high-resolution timing signal is critical for fuel injection synchronization. On GM Vortec engines, losing both high-resolution timing signals can prevent starting. Losing only signal B while signal A remains functional may allow the engine to start but run poorly. If your vehicle cranks but will not start alongside P0375, the timing signal is a likely contributor.