Guide To P0372 OBD Error Code Solutions

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OBD-II Code Decreased engine performance is defined as a Timing Reference High Resolution Signal "A" Too Few Pulses. This code is detected when some high-resolution pulses are missing from the optical sensor to the PCM. It's based on a comparison between the number of pulses that were detected since the last pump cam pulse and the number of the pulses that should have occurred. There are approximately 64 high resolution pulses for every cam pulse. The letter A simply indicates an area of the involved circuitry rather than a specific component.

Diagnostic trouble code P0372 is technically described as Timing reference, high resolution signal A -too few pulses. It is a generic powertrain code, which means it applies to OBD-II equipped vehicles which have an engine position sensor. The optical sensor provides a high-resolution signal to the Powertrain Control Module (PCM) by counting pulses on the sensor disk located in the injection pump. The high resolution is one of the most important inputs by the PCM for fuel control and timing. This test monitors the number of high-resolution pulses which have been missed (not detected). There should be about 64 pulses for every cam pulse, and when the number actually detected deviates from this norm, the P0372 will store. Due to this code you may start facing problems like decreased engine performance and your engine may not start. We recommend you to immediately diagnose and repair your vehicle when such symptoms occur.

What causes this problem with the Timing Reference High Resolution Signal A Too Few Pulses?

• Defective distributor position sensors
• Optical sensor harness is open or shorted
• Frayed optical sensor
• Sensor circuit has loose or damaged connections
• Faulty distributor
• Faulty PCM

1. Powertrain Control Module - The Powertrain Control Module PCM is an on-board electronic control unit that primarily controls the charging, emission and transmission systems of the vehicle. Ensure its efficient functioning as it is a brain for your vehicle.
2. Fuel Injector - Fuel injector is an electronically controlled mechanical device that is responsible for spraying (injecting) the right amount of fuel into the engine so that a suitable air/fuel mixture is created for optimal combustion. Repair or replace it if found frayed.
3. Camshaft Sensor - Camshaft sensors detect the camshaft position for the injection sequence. A faulty camshaft sensor could also be a cause for this DTC so replace it immediately when discover it faulty.
4. Crankshaft Sensor - The crankshaft position sensor is a vital electronic device located in the engine of a car. Its purpose is to register the rate at which the crankshaft spins. Make sure it works properly to avoid all the associated codes.
5. Optical Sensor - An optical sensor converts light rays into electronic signals. It measures the physical quantity of light and then translates it into a form that is readable by an instrument.
6. Connectors – Replace all the damaged and corroded connectors to avoid any trouble code.
7. Cam Reluctor - Reluctor is operated by the distributor shaft to produce timed electric signals, which are amplified and used to control the current to the induction coil. Replace or repair it to avoid any serious issue in near future.

Below are the common symptoms for the code P0372. If you experience any of these please bring your vehicle to a reputable repair facility. It may take some time before the Check Engine light comes on, so it’s important to be aware of any noticeable signs of a problem.

• Misfiring of engine
• Spark knocking
• Decreased fuel mileage
• Difficulty in starting engine
• Illuminated check engine light

The diagnostic trouble code P0372 can be complex and exhaustive to track down and repair. The task may involve multiple repairs, as well as specialized tools and equipment. If you doubt this repair is out of your skill level, it’s best to contact a qualified mechanic and have them fix this issue. The possible solutions for this trouble code include:

• Camshaft, distributor hall effect, and crankshaft sensor replacement
• Replacement of corroded or damaged wiring or connectors
• Distributor replacement

Note: If you decide to fix this diagnostic process yourself, make sure that you disconnect the wiring connectors from the PCM side before checking resistance values on the harness side. This will prevent damage to the PCM.

Troubleshooting steps may differ depending upon manufacturer. A good starting point is always a technical service. Several tools may be required to successfully diagnose this code.

• Inspect the stored trouble code and record the freeze frame data using a scan tool.
• Clear any stored codes and take a test drive and check if the code return.
• With the help of tachometer observe the engine running to see if there is an RPM signal.
• Inspect the crankshaft position sensor, crankshaft gear, and connectors and wiring for damage.
• Test the Crankshaft Position Sensor (CPS) system to ensure the reference voltage matches specifications.
• Check for system continuity with the help of Ohmmeter.
• Check the distributor for damage, wobble, or too much end-play.

Common Mistakes When Diagnosing the P0372 Code

Make sure you check crankshaft, camshaft, and distributor sensors thoroughly before replacing them. Crank and cam reluctor rings should also be checked when replacing sensors. Usually people replace these things without a thorough check wherein at the end the actual problem is discovered with some other part.