Fault code P0371 – timing reference high resolution signal “A” too many pulses

Fault code P0371 is called “Timing Reference High Resolution Signal “A” Too Many Pulses” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.

Technical description and explained code P0371

OBD-II fault code P0371 is a generic fault code defined as “too many pulses in high resolution “A” signal timing control. It is set when the powertrain control module (PCM) detects too many pulses in the timing signal.

Fault code P0371 – timing reference high resolution signal

The code mainly refers to a problem in the engine position sensor circuit, aka crankshaft position sensor. Although, failure of the crankshaft position sensor itself can also cause this code to set.

In order for the PCM to effectively monitor and control engine RPM, fuel injection strategy, ignition timing, and fault diagnostics. It needs a reference signal that tells the PCM where the crankshaft, and therefore the #1 piston, is during crankshaft rotation.

In other words, the PCM needs to know how many degrees of rotation the crankshaft has gone through during its rotation relative to a fixed starting point. In a full-featured system, the generated signal is fed to the PCM through a special signal circuit, or a variable resistance in the case of two-wire sensors.

The synchronization signal is generated by a sensor whose magnetic field is interrupted by the teeth of a gear wheel. Which may be located on the crankshaft pulley, camshaft or inside the fuel pump on some diesel engines.

Code P0371 is set when the PCM detects too many pulses in the engine position sensor “A” signal. The “A” indicates a problem in part of the system circuit, not a specific symptom or component.

Symptoms of vehicle malfunctions

The main signal that an error P0371 has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.

It can also be warning signs such as:

  1. The “Check engine” control lamp on the control panel will light up (the code will be recorded in the memory as a malfunction).
  2. The vehicle engine may be unstable.
  3. Ignition skips in the engine cylinders may occur.
  4. Increased fuel consumption.
  5. Possible problems with engine starting.
  6. The engine may stall or start poorly.

The severity of fault code P0371 may vary from medium to heavy. If the vehicle engine is unstable with this error, it is recommended to correct it as soon as possible.

Factors that can cause this error code

The error code P0371 can mean that one or more of the following problems have occurred:

  • Faulty engine position sensor.
  • Sensor wiring is too close to spark plug wiring (interference may occur).
  • Loose connection of engine position sensor wires.
  • Damaged or clogged gear ring from which data is received.
  • Contaminated oil.
  • Poor connection of wires in PCM.

How to fix or reset OBD-2 code P0371

Some suggested steps for troubleshooting and fix the error code P0371:

  1. Check that the wiring is not routed too close to secondary ignition components (coils, spark plug wires, etc.).
  2. Visually inspect the sensor wiring for signs of burning, discoloration indicating melting or wear.
  3. Inspect the engine position sensor for damage.
  4. Carefully inspect the gearwheel through the sensor hole (if possible) for missing teeth or damage.
  5. If the gear is not visible from the outside, a visual inspection can only be made by removing the camshaft or intake manifold (depending on engine design).
  6. When all the items are done and the error has not gone away, replace the sensor. In most cases this will solve the problem.

Often replacing the sensor will fix the P0371 error code, but not necessarily. Therefore, it is important to do a check of all items.

Diagnose and repair of problems

Error P0371 refers to an electrical circuit problem, but the engine position sensor should not be overlooked. The sensor itself can fail, but replacing it does not always solve the problem. Therefore, you should check the electrical circuit with a digital voltmeter.

Make sure that the connector on the sensor is secure. Also, inspect the wiring harness for damage. For example, damage from recent engine repairs, shocks, or rodent damage.

Check the sensor

Disconnect the sensor and measure the resistance. If it reads infinity, there is an open or short circuit. If it reads 0 ohms, you can tell that the sensor itself is defective.

It is best to use a digital oscilloscope to check the signal. But you can also get a rough estimate by putting the voltmeter in alternating voltage mode. The test should give at least 20 mV.

Electrical inspection

Disconnect the ECM and CMP controller connectors, then place a short jumper on the engine position sensor connector terminals. A small paper clip or wire can be used for this purpose.

On the ECM controller side, check the resistance in the circuit itself. It should be less than 0.1 ohm. If it is more, ECM will not be able to detect the signal. Therefore, you need to look for a broken wire or corrosion.

Remove the jumper and check the circuit for a break, if there is resistance, a short circuit has probably occurred. Water in the connector can easily cause this. Check for a ground fault by taking one of the leads and connecting it to “ground” or the negative battery terminal.

If there is no problem in the engine position sensor or its wiring, P0371 is probably just an auxiliary fault code. Pay attention to a jumped timing belt. There may also be a faulty signal, crankshaft position sensor circuit, or engine misfire.

On which vehicles does this problem occur most frequently

Fault code P0371 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:

  • BMW
  • Chevrolet
  • Dodge
  • Ford (Focus)
  • GMC
  • Hyundai
  • Porsche (Cayenne)
  • Tata
  • Toyota (Avensis)
  • Volkswagen
  • GAZelle

Fault code P0371 can sometimes be found with other errors. The most common are the following: P0370, P0372, P0373, P0374.

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