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All codes/P0378

P0378

Timing Reference High Resolution Signal B Intermittent/Erratic Pulses

High severity

Timing reference signal B pulses are erratic — connector or wiring intermittent, contamination on tone wheel, or sensor partially failed.

Timing reference signal B pulses are erratic — connector or wiring intermittent, contamination on tone wheel, or sensor partially failed.

Common causes

  • Intermittent connector or contamination

    One of the most commonly reported causes for this code — check this first.

    high

    Typical part cost: $90-660

  • Connector with intermittent contact under vibration

    Less common, but worth ruling out after the more likely causes.

    low

    Typical part cost: $90-660

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First things to check

  1. 1Confirm the code with a scan tool and check for additional related codes.
  2. 2Inspect the relevant sensors, wiring, and connectors for damage or corrosion.

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Tools you may need

Already have a compatible scanner? Use it. If not, a Bluetooth OBD2 adapter can help you confirm engine codes and check supported live sensor data before replacing parts.

Illustration of a Bluetooth OBD2 adapter, not a product photo

Basic checks

Veepeak OBDCheck BLE

A Bluetooth LE adapter for reading standard engine codes and supported live data.

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Illustration of a Bluetooth OBD2 adapter, not a product photo

Regular diagnostics

vgate iCar Pro BLE 4.0

A Bluetooth LE adapter with an automatic sleep feature for routine code and sensor checks.

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Illustration of a Bluetooth OBD2 adapter, not a product photo

Another option

OBDLink CX

A Bluetooth LE adapter to consider when comparing supported vehicles and diagnostic apps.

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Illustrations shown, not product photos. Check vehicle, phone and app compatibility before buying. These adapters do not guarantee access to ABS, airbags or manufacturer-specific systems. Clearing a code does not repair the fault and can reset emissions readiness monitors.

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Related codes

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Frequently asked questions

What does P0378 mean?

P0378 means "Timing Reference High Resolution Signal B Intermittent/Erratic Pulses". It is a generic OBD-II code that points to a fault in the ignition system or misfire.

What are the most common causes of P0378?

intermittent connector or contamination; connector with intermittent contact under vibration; harness routed against vibrating component — these are the most commonly reported causes. Verify with a proper diagnosis before replacing parts, or use the Wrenchify app for a vehicle-specific diagnosis.

Can I keep driving with this code?

This code points to a problem that can cause damage or affect safety. Avoid driving and have the vehicle diagnosed promptly. Use the Wrenchify app for a full diagnosis specific to your vehicle.

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