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P0078 Code – What Does It Mean & How To Fix It

This is one of the most frequent OBD2 trouble codes. Read the full article below to know what it means, how to fix it, and what other codes may show related to it.


An issue with the intake valve control solenoid circuit for Bank 1 is indicated by the OBD-II fault code P0078, which is a Diagnostic Trouble Code (DTC). The intake valve control solenoid is expressly mentioned as having a high voltage situation in this error code.


When a P0078 code is triggered, this indicates that the solenoids of the Bank 1 Intake control valve are operating in an extreme voltage condition. In order to ensure optimum performance and fuel efficiency, an Intake valve Control solenoid plays a vital role in controlling airflow into the engine.


The P0078 DTC code may have a number of possible reasons, including:

  • Intake valve control solenoid malfunction: A high voltage issue may be caused by internal electrical problems with the solenoid or by it being stuck in the open position.
  • Wiring or connection issues: Corroded terminals, damaged wiring, or loose connections can all affect the electrical circuit and result in excessive voltage.
  • Engine control module (ECM) malfunction: An ECM that isn’t working properly may send the solenoid the wrong signals or too much voltage.
  • Short to power or ground: In the intake valve control solenoid circuit, a short circuit to power or ground might result in a high voltage situation.


The P0078 code may also be accompanied by a number of typical symptoms, such as:

  • Check Engine Light (CEL) On: The most glaring indication of a problem is the illumination of the CEL on the dashboard of the car.
  • Reduced engine performance: The car’s overall performance and power may be affected.
  • Poor fuel economy: The compromised airflow caused by the high voltage condition can lead to decreased fuel efficiency.
  • Rough idling: The engine may run unevenly or exhibit irregular idle speed.


To accurately diagnose the P0078 code, it is recommended to follow these steps:

  • OBD-II scanner: Use an OBD-II scanner to retrieve the specific code and any related codes.
  • Visual inspection: Conduct a thorough inspection of the intake valve control solenoid, wiring, and connectors to identify any visible issues or damage.
  • Testing the intake valve control solenoid: Use a multimeter to measure the resistance and voltage of the solenoid.
  • Inspecting the wiring and connections: Check for damaged wiring, loose connections, or corroded terminals.
  • Testing the ECM: If necessary, conduct tests to verify the functionality of the ECM.

Common mistakes

The following typical errors should be avoided while diagnosing and fixing the P0078 code:

  • Ignoring pertinent codes: Examine and fix any further relevant codes that may be a factor in the problem.
  • Insufficient visual examination: Make sure you do a complete inspection of the wiring, connections, and other parts for any obvious issues.
  • Failing to address root causes: Simply clearing the code without resolving the underlying issue can lead to recurring problems.

How serious is this?

Depending upon the vehicle and its particular circumstances, the level of P0078 code may differ. Although the vehicle may continue to operate, it is not advisable to ignore this issue. Prolonged operation with a faulty intake valve control solenoid can lead to engine damage, reduced performance, and decreased fuel efficiency.

What repairs can fix the code?

repair manuals

It might be essential to make the following repairs to fix the P0078 error code:

  • Replacement of the solenoid that controls the intake valve: If the solenoid is broken or jammed, it has to be changed.
  • Repairing or replacing damaged wiring or connectors: Any issues with the wiring or connections must be addressed.
  • Checking for short circuits: Inspect the intake valve control solenoid circuit for any short circuits to power or ground and repair them as necessary.
  • ECM replacement or repair: If the ECM isn’t working properly, it may need to be fixed.

Related codes

Some related codes that may be associated with the P0078 DTC code include:

  • P0075: Intake Valve Control Solenoid Circuit Bank 1
  • P0076: Intake Valve Control Solenoid Circuit Low Bank 1
  • P0077: Intake Valve Control Solenoid Circuit High Bank 1


The P0078 DTC code indicates a high voltage condition in the intake valve control solenoid circuit for Bank 1. In order to ensure that engine damage is avoided and vehicle performance remains as good as possible, this code needs to be dealt with immediately.

If the problem is correctly diagnosed and repaired, you can solve it and get your vehicle working again. Ensure that the P0078 DTC Code is correctly diagnosed and repaired by an expert technician.

P0078 Code – What Does It Mean & How To Fix It