What does the P0077 fault code mean?
The P0077 fault code, applicable to all car manufacturers, means “Intake Valve Control Solenoid Circuit High (Bank 1)“.
Background Information: The camshaft controls the opening and closing of the valves. In a variable valve timing system, the electronic camshaft actuator (or oil control valve, OCV) adjusts the camshaft angle by changing the oil pressure to the camshaft adjuster (mechanical) according to instructions from the engine control module (ECM), ensuring that the valves open and close at the optimal time. This fault code appears if the intake camshaft actuator circuit voltage is higher than the calibrated maximum value.
Symptoms of P0077 Error Code:
- Loss of engine power
- Unstable idle
- Difficulty starting the engine
- Increased fuel consumption
- Check engine light illuminated
Main Causes of P0077 Error Code:
- Open or short circuit in the VVT valve circuit
- Damaged VVT solenoid valve
- Oil sump contamination
- Engine control unit (ECM/PCM) failure
- Low or dirty engine oil
How to diagnose error code P0077?
- Connect an OBD2 diagnostic scanner and read the error codes.
- Check the VVT solenoid valve connector and wiring for damage or corrosion.
- Measure the voltage and resistance at the valve contacts with a multimeter.
- Check the valve itself: the valve should make a “click” sound when energized – this is an indication of its performance.
- If necessary, replace the valve or check the engine control unit.
Possible Causes and Diagnostic Methods
| Possible Cause | How to Check? |
|---|---|
| Open VVT circuit | Resistance measurement and visual inspection |
| Short circuit | Housing contact test |
| VVT valve failure | Oscilloscope test or replacement with a known good one |
| ECM/PCM failure | OBD2 scanner diagnosis |
| Low oil level | Dipstick check of oil level and quality |
Tools needed: OBD2 scanner, multimeter, oscilloscope (for advanced diagnostics), automotive tool kit
How to fix error code P0077? (Solutions to the Problem)
Simple Repair Methods
- Clean the VVT valve connector and wiring
- Replace damaged cables or chips
- Engine oil and oil filter replacement
- Reset the error after resolving the cause
In-depth Diagnostic and Repair Solutions
- Replace the defective VVT solenoid valve
- Inspect and repair the engine control unit (if necessary)
- Flush the VVT system and oil pan
Troubleshooting by Symptoms
| Symptom | Possible Solution |
|---|---|
| Power outage | Check and replace the VVT valve |
| Unstable idle | Clean the connector, check the wiring |
| Increased fuel consumption | Change oil, eliminate short circuits |
| Check engine light | VVT scan and troubleshooting |
Common P0077 Error Codes in Vehicles
Toyota P0077: In Toyota models, the P0077 error may be caused by oil contamination or a faulty VVT valve. Changing the oil and cleaning the contacts usually helps.
Hyundai P0077: Hyundai models equipped with Theta series engines are prone to this error due to weak connector contact points and poor oil quality.
Ford P0077: In Ford Focus, Fusion, and other models equipped with the Ti-VCT system, the problem may be due to wiring faults or ECM malfunctions.
Nissan P0077: For Nissan models (e.g., Altima, X-Trail), the error may be due to clogged oil passages affecting the VVT system.
BMW P0077: In BMWs equipped with Valvetronic engines, the P0077 error occurs when the solenoid valve is worn and there are problems with the control module.
P0077 Frequently Asked Questions
Can you drive with error code P0077?
This is not ideal, as valve timing irregularities can lead to decreased engine performance and increased component wear.
Can the P0077 error be caused by engine oil?
Yes, dirty or low-quality oil can clog the VVT passages and interfere with the operation of the solenoid valve.
Is it possible to reset the error code without fixing the problem?
You can temporarily clear the error with a scanner or by disconnecting the battery, but the fault code will reappear if the root cause of the problem persists.
At what mileage does the P0077 error most commonly occur?
This error usually appears after driving 100,000 kilometers, especially when oil and filters are not changed regularly.
Will the P0077 error disappear on its own?
Rarely. Usually, the cause of the error needs to be addressed: cleaning the valve, changing the oil, or repairing the wiring.
Related OBD2 errors for P0077:
P0010 – A Camshaft Position Actuator Circuit/Open (Bank 1)
P0011 – A Camshaft Position – Timing Over-Advanced or System Performance (Bank 1)
P0078 – Exhaust Valve Control Solenoid Circuit (Bank 1)
Important! Error P0077 indicates a problem with the VVT valve control circuit in the first cylinder bank. It is usually caused by a broken wire, contaminated oil, or a faulty solenoid. Regularly change the oil and filter, especially in the variable valve timing system. This will prevent errors like P0077 and extend engine life.