P0340 – Camshaft position (CMP) sensor A, bank 1 circuit malfunction (Mitsubishi)

Reinier

By Reinier (Contact Me)
Last Updated 2021-01-05
Automobile Repair Shop Owner

Trouble CodeFault LocationProbable Cause
P0340 Camshaft position (CMP) sensor A, bank 1 circuit malfunction Wiring, CMP sensor, ECM

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What Does Code P0340 Mean?

Special note on trouble code P0340 and Mitsubishi vehicles: While DTC P0340 is a generic code that affects all OBD II compliant vehicles, the most common causes of this code sometimes vary between most vehicle makes. This article will therefore deal with code P0340 as it applies specifically to Mitsubishi vehicles.

OBD II fault code P0340 is a generic trouble code that is defined as “Camshaft position (CMP) sensor A – Bank 1 – circuit malfunction” and is set when the PCM (Powertrain Control Module) detects a failure, defect, or malfunction in the control, signal, or reference voltage circuit(s) of the position sensor that is associated with the intake camshaft on Bank 1. Note that “Bank 1” refers to the bank of cylinders on V-type engines that contains cylinder #1.

While several details of the ignition systems on Mitsubishi vehicles differ somewhat from the ignition systems of most other vehicle brands, Mitsubishi ignition systems are not so different from other ignition systems that they are difficult to diagnose and repair.

For instance, unlike the ignition systems of most other vehicle brands, the PCM on Mitsubishi applications does not require input data from both the crankshaft and camshaft position sensors before the engine can be started. In the case of Mitsubishi systems, the PCM only requires input data from the camshaft position sensor, which is used to detect the TDC (Top Dead Center) position of piston #1.

This information is used to calculate appropriate ignition and fuel injection timing strategies. Thus, while the engine is cranking, the PCM “tracks” the position of piston #1 via the position of the intake camshaft. While this system works well, its continued operation requires that all engine timing components are aligned correctly and in good condition, since the crankshaft’s position is not correlated directly to that of the camshaft via the crankshaft position sensor as is the case on most other applications.

We need not delve into the technical details of each type of camshaft position sensor in use on Mitsubishi vehicles here, beyond saying that Mitsubishi vehicles are typically fitted with Hall-effect sensors. These sensors create electrical signals when a rotating reluctor ring or protrusion on the camshaft passes in front of the sensing element. In terms of operation, the camshaft position sensor is supplied with a 5-volt reference voltage that switches between “ON” and “OFF” states as the camshaft rotates.

By monitoring the state of the signal, the PCM can correlate the crankshaft’s position with that of the camshaft as a means to verify that the engine’s valve, ignition, and injection timing are all within a specified range before starting the engine. Therefore, if the PCM does not receive a plausible signal (or any input signal) from the camshaft position sensor for four consecutive seconds during cranking, the PCM will recognize that it cannot control the fuel delivery and ignition systems effectively, and it will set code P0304 and illuminate a warning light as a result, which brings us to-

What causes code P0340 on Mitsubishi vehicles?  

Camshaft position sensor failures caused by heat and vibration are by far the most common cause of code P0340 on many, if not most Mitsubishi vehicles. Note that this true even for OEM sensors; see the section on Common Causes for more details on other possible causes of this code on Mitsubishi applications.

Where is the P0340 sensor located?

This image shows the location of the camshaft position sensor on a 2007 Mitsubishi Galant. Note that while the sensor is easily accessible in this example, the location of the camshaft position sensor varies greatly between Mitsubishi applications, and in some cases, unrelated engine components may have to be removed and/or disassembled to gain easy access to the sensor.

Therefore, it is recommended that you consult reliable service information for the affected application to locate and identify the relevant sensor correctly. Failing to locate the correct sensor could cause misdiagnoses and possibly the unnecessary replacement of parts and components.

What are the common causes of code P0340?

Apart from camshaft position sensor failures caused by heat and vibration, other causes of code P0340 on Mitsubishi vehicles could include one or more of the following-

  • Damaged, burnt, shorted, disconnected, or corroded wiring and/or connectors in the sensors’ wiring harness. Note that due to the relative inaccessibility of the sensor and its wiring on many Mitsubishi models, these kinds of issues often go unnoticed until the sensor and/or associated wiring fails
  • The use of most brands of aftermarket camshaft position sensors
  • Failed or failing PCM, but note that unlike most other generic codes, PCM failures are a distinct possibility. Nonetheless, all other diagnostic avenues must be exhausted before any control module is reprogrammed or replaced

What are the symptoms of code P0340?

The most common symptoms of code P0340 on Mitsubishi vehicles a much the same across all Mitsubishi applications and could include one or more of the following-

  • Stored trouble code and illuminated warning light, but not that it is rare for multiple other codes to set along with P0340
  • A no-start condition may be present
  • In cases of incipient sensor failure, the engine may run roughly under some operating conditions, or the engine may exhibit random misfires

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