Causes of the P0004 code

Cause of occurrence Engine or automatic transmission error P0004:

Possible causes and tips for eliminating the malfunctions that led to the error:

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Causes:

Loss of power or the engine may stop starting altogether.

The reasons:

• faulty state of the fuel supply regulator.
• faulty condition of the fuel regulator wiring (short circuit, corrosion, scuffed wires, other mechanical damage).

Troubleshooting tips:

If a P0004 error occurs, check the gaskets in the high pressure fuel pump. In diesel vehicles, the cause may be the return of the fuel.

Visually check the wiring, connectors, fuses and relays related to the electrical circuit of the fuel regulator and the electronic engine control unit. Look for obvious scuffs and breaks in the wires. If found, repair the damaged section of the wire. Also, if necessary, replace the defective fuse or relay.

If no external signs of damage are found, contact the service center and diagnose the high pressure circuit.

DTC Engine or automatic transmission error P0004

On our resource, you have the opportunity to ask questions and share your own experience in troubleshooting the P0004 error. After asking a question within a few days, you can find the answer to it.

Taking into account the fact that OBD2 errors in the operation of the engine or other electronic systems of the car do not always directly indicate an inoperative element, and the fact that different brands and models of cars the same error can occur as a result of a malfunction of completely different elements of the electronic system, we created this algorithm for help and exchange of useful information.

We hope, with your help, to form a cause-and-effect relationship for the occurrence of a particular OBD2 error in a particular car (make and model). As experience has shown, if we consider a certain brand-model of a car, then in the overwhelming majority of cases the cause of the error is the same. 

If the error indicates incorrect parameters (high or low values) of any of the sensors or analyzers, then most likely this element is working, and the problem must be looked for, so to speak, “upstream”, in the elements of which the sensor or probe analyzes the work.

If an error indicates a permanently open or closed valve, then here it is necessary to approach the solution of the issue wisely, and not to change this element thoughtlessly. There may be several reasons: the valve is clogged, the valve is stuck, the valve receives an incorrect signal from other faulty components. 

Errors in the operation of the OBD2 engine and other vehicle systems (ELM327) do not always directly indicate an inoperative element. The error itself is indirect data about a malfunction in the system, in a sense, a hint, and only in rare cases is a direct indication of a faulty element, sensor or part. Errors (error codes) received from the device, the scanner require correct interpretation of the information, so as not to waste time and money on replacing the working elements of the car. The problem often goes deeper than meets the eye. This is due to the circumstances that informational messages contain, as mentioned above, indirect information about the disruption of the system.

Here are a couple of common examples. If the error indicates incorrect parameters (high or low values) of any of the sensors or analyzers, then most likely this element is working, since it analyzes (gives out certain parameters or values), and the problem must be looked for, so to speak, “upstream”, in the elements whose work is analyzed by the sensor or probe. 

If an error indicates a permanently open or closed valve, then here it is necessary to approach the solution of the issue wisely, and not to change this element thoughtlessly. There may be several reasons: the valve is clogged, the valve is stuck, the valve receives an incorrect signal from other faulty components.

Another point that I would like to note is the specificity of a particular brand and model. Therefore, having learned an error in the operation of the engine or other system of your car, do not rush to make hasty decisions, but approach the issue in a comprehensive manner.

Our forum was created for all users, from ordinary car enthusiasts to professional car electricians. Drop by drop from each and everyone will be useful.