P0075, P0076, and P0077: Intake valve control solenoid circuit (Bank 1)

If you own a car with variable valve timing (VVT) system, you may encounter one of these trouble codes: P0075, P0076, or P0077. These codes indicate a problem with the intake valve control solenoid circuit on bank 1, which is the side of the engine with cylinder #1.

In this article, we will explain what these codes mean, what causes them, what symptoms they produce, and how to fix them.

What are P0075, P0076, and P0077 Codes?

P0075 Intake valve control solenoid circuit (Bank 1):

Means that the intake valve control solenoid circuit on bank 1 is out of the specified voltage range or intermittent. The intake valve control solenoid is a device that regulates the oil flow to the intake valve timing control unit, which adjusts the position of the camshaft to optimize the engine performance and efficiency. The solenoid is controlled by the engine control module (ECM) using a pulse width modulated (PWM) signal.

P0076 Intake valve control solenoid circuit low (Bank 1):

Means that the intake valve control solenoid circuit on bank 1 has a low voltage. This could be caused by a short to ground in the wiring or the solenoid itself.

P0077 Intake valve control solenoid circuit high (Bank 1):

Means that the intake valve control solenoid circuit on bank 1 has a high voltage. This could be caused by a poor connection, an open circuit, a short to power, or a faulty ECM.

These codes are similar to each other and may also be accompanied by P0026 code, which indicates a problem with the intake valve timing control performance123.

What Causes P0075, P0076, and P0077 Codes?

There are several possible causes for these codes, such as:

• Faulty intake valve control solenoid
• Damaged or corroded wiring harness or connectors
• Loose or disconnected terminals
• Short to ground or power in the circuit
• Faulty ECM

To diagnose these codes, you will need a scan tool that can read the engine functions and a digital volt ohm meter (DVOM) that can measure voltage and resistance. You will also need a wiring diagram and a repair manual for your specific vehicle model.

What Symptoms Do P0075, P0076, and P0077 Codes Produce?

These codes may cause some noticeable symptoms in your vehicle, such as:

• Check engine light illuminated
• Poor acceleration and decreased fuel economy
• Rough idle or engine hesitation
• Engine performance issues

These symptoms may affect your driving safety and comfort, so it is important to address these codes as soon as possible.

How to Fix P0075, P0076, and P0077 Codes?

To fix these codes, you will need to follow these steps:

• Locate the intake valve control solenoid on bank 1. It is usually located on the intake manifold side of the cylinder head.
• Unplug the electrical connector from the solenoid and inspect it for any signs of damage, corrosion, or loose wires. If you find any problems, repair or replace the connector as needed.
• Check the resistance of the solenoid using the DVOM. Set the meter to ohms and measure the resistance between the two terminals on the solenoid. Compare your reading with the factory specifications or a known good solenoid. If the resistance is out of range or over limit, replace the solenoid.
• Check for a short to ground in the solenoid using the DVOM. Set the meter to ohms and connect one lead to a good ground and the other lead to each terminal on the solenoid. If there is any resistance present, replace the solenoid.
• Check the wiring harness from the solenoid to the ECM for any signs of damage, corrosion, or loose connections. Unplug the connectors from both ends and check for continuity and resistance using the DVOM. Set the meter to ohms and measure between each end of each wire in the harness. If there is an open or high resistance in any wire, repair or replace it as needed.
• Check for voltage in the circuit using the DVOM. Set the meter to volts and connect one lead to a good ground and the other lead to each wire in the harness at both ends. Turn on the ignition and check for voltage readings. If there is no voltage present at either end of any wire, check for a blown fuse or relay in the circuit and replace it as needed. If there is voltage present at one end but not the other, check for a short to ground or power in the wiring and repair it as needed.
• Check the ECM for any signs of damage or malfunction. If you suspect that the ECM is faulty, you may need to use a scan tool that can communicate with the ECM and perform some tests to confirm its condition. If the ECM is confirmed to be faulty, replace it with a new or remanufactured unit.

After performing these steps, clear the codes using the scan tool and test drive the vehicle to see if the codes return. If they do, you may need to repeat the diagnosis or seek professional help.

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