OBD-II Trouble Code P0371: Timing Reference High Resolution - Signal A - Too Many Pulses

P0371 code definition

The P0371 code is a generic powertrain code related to an ignition system error or misfire. In this case, the engine control module (ECM) has found a fault or malfunction with the high resolution timing reference signal A.

What the P0371 code means

A code P0371 will be stored when the ECM has detected a variation in the high resolution engine timing signal, in which a preset number of degrees was exceeded. The allowed degrees of variation will depend on your vehicle make and model, it is recommended to check your vehicle service manual for more information.

Typically, auto manufacturers use an electromagnetic crankshaft position sensor in two ways, both of which use either a reluctor ring or teeth to create a square waveform pattern that gives the ECM the crankshaft position. One manufacturer design will utilize the crankshaft position sensor for misfire detection, and the other uses the sensor for the calculation of spark timing and ignition control.

Signal A pertains to a specific area of system circuitry, it is recommended to check your vehicle service manual for specifics as to the location of signal A in your specific vehicle make and model.

What causes the P0371 code?

Several problems may cause a P0371 code including:

• Damaged or defective camshaft position sensor
• Damaged or defective crankshaft position sensor
• Damaged or defective distributor cap sensor
• Damaged or defective crank and cam reluctor rings

What are the symptoms of the P0371 code?

Symptoms of a P0371 code may include:

• Check engine or warning light may illuminate
• Decrease in fuel economy
• Spark knock when vehicle accelerates
• Engine misfire
• Vehicle may not start
• Vehicle may not exhibit any symptoms at all, aside from a stored P0371 code.

How does a mechanic diagnose the P0371 code?

A mechanic may use several methods to diagnose a P0371 trouble code, including:

• Utilize an OBD-II scanner to check for a stored P0371 trouble code
• Visually inspect electrical wiring and related connectors and components for signs of damage
• When the engine is running, check for an engine rpm signal using a scanner or through looking at the tachometer.
• Visually inspect the crankshaft gear, crankshaft position sensor, and sensor connector for any signs of damage of defect
• Test the crankshaft position sensor system for reference voltage signal
• Test camshaft position sensor
• Utilize a oscilloscope to test the crankshaft position sensor for the proper waveform pattern
• Test circuits for correct resistance and voltage

Common mistakes when diagnosing the P0371 code

While it’s possible that camshaft, crankshaft, and distributor sensors could be the problem, they are often immediately assumed to be the problem and replaced. It is recommended to check all electrical circuitry and wiring, and check for mechanical distributor malfunction, prior to replacing any sensors.

How serious is the P0371 code?

Because a vehicle’s safe driving operation most likely will be impacted due to faults that store a P0371 code, this code is considered a potentially serious code. When this code appears, it is recommended to immediately take your vehicle to your local service center or mechanic for repair and diagnosis.

What repairs can fix the P0371 code?

Several repairs can fix a P0371 trouble code and include:

• Repair damaged or defective electrical wiring and related components
• Replace damaged or defective crankshaft position sensor
• Replace damaged or defective camshaft position sensor
• Replace damaged or defective distributor sensor
• Clear all codes, test-drive the vehicle, and rescan to see if any codes reappear

Additional information related to a P0371 code

If you need to replace the camshaft and/or crankshaft sensors, it is recommended to do so as a set and to utilize original equipment manufacturer (OEM) sensors. Also, if replacing sensors, be sure to check crank and cam reluctor rings for damage or need of replacement.

Need help with a P0371 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.