Error Code P0370: What It Means & What To Do?

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OBD-II Code Decreased engine performance is defined as a Timing Reference High Resolution Signal "A". This code is detected when a number of high-resolution pulses missing per every 8 cam reference pulses. These pulses provide the PCM with information required to confirm fuel is delivered correctly, and that the right air mixture is provided for combustion. A code P0370 is set when the PCM detects a malfunction with the "A" engine position sensor signal. The “A” pertains more to an area of the system circuitry than to a particular component.

OBD II fault code P0370 is a generic code that is defined as “Timing reference, high resolution signal A – malfunction”, and is set when the PCM fails to detect a timing reference signal. The powertrain control module (PCM) requires a timing reference signal to determine engine speed and position. This is accomplished by means of an engine position sensor, such as a crankshaft, camshaft or fuel pump position sensor. There are two basic types of engine positions sensors: Hall-Effect and permanent magnet. Half - effect sensor receives a reference voltage (usually 5-volts) from the PCM, and is triggered by a reluctor wheel where as Permanent magnet (PM) sensors produce their own AC voltage based on their proximity to a rotating reluctor wheel.

If the PCM detects variations in the high resolution engine timing signal that exceed a predetermined number of degrees, a code will be stored and a service engine soon lamp may be illuminated.

What causes this problem with the Timing Reference High Resolution Signal A Malfunction?

• Failed Crankshaft Position Sensor
• Faulty Fuel injection control module
• PCM failure
• Wiring problem
• Damaged reluctor wheel
• Substandard oil

1. Optical Sensor - An optical sensor converts light rays into an electronic signal. The purpose of an optical sensor is to measure a physical quantity of light and, depending on the type of sensor, then translates it into a form that is readable by an integrated measuring device (PCM). Kindly replace the frayed optical sensors to avoid associated trouble codes and any serious problems.
2. Wiring Harness - Wiring Harness is an assembly of electrical cables or wires which transmit signals or electrical power. If it has any kind of cuts or any sign of damage, replace it immediately.
3. PCM - Powertrain Control Module (PCM), we all know that it is a most crucial part of the vehicle like a brain in human body and plays an important role in smooth functioning of your vehicle. However, it is very rare that it fails but if by any chance you discover if faulty or failed, repair or replace it as required without any second thought.

It is very important to know the common symptoms of this trouble code because without knowing the symptoms you would not be able to discover it and fix it. Below mentioned are the symptoms for the OBD Code P0370.

• Poor engine performance
• Severe misfires
• Difficulty to start
• Increased fuel consumption
• Illuminated check engine light

Initially you might not face any significant drivability problems with this code but as the reference signal from the optical sensor is crucial to the PCM’s ability to meter fuel flow. So, it is very important to have it repaired as soon as possible. The most common repair for the P0370 code is replacing a failed reference optical sensor. Apart from this the other repairs or replacements that can help to fix this trouble code P0370 are as follows:

• Cleaning the optical sensor
• Repairing or replacing the wiring harness
• Repairing or replacing damaged/corroded connections
• Replacing the PCM

Following are some easy steps to diagnose this trouble code P0370. Though it is not much difficult to diagnose this code but we always advise you to take your vehicle to an experienced diagnostician to get it diagnose.

• First connect an OBD II scanner to the car’s communication port, which is usually located under the dash on the driver side.
• Read the codes stored in the computer and then clear them.
• Test Drive the vehicle to see if the code resets.
• Thoroughly inspect the wiring harness in timing reference optical sensor to see if there is any damage or breakage.
• Check the connections.
• Clean the sensor and test once again.

Common Mistakes When Diagnosing the P0370 Code

Unnecessary replacement of crankshaft, camshaft, and distributor sensors, when mechanical distributor failure is the culprit, are fairly common. Crank and cam reluctor rings should also be checked when replacing sensors.