The OBD2 code P0077 indicates a problem with the “Intake Valve Control Solenoid Circuit High Bank 1”. This means the car’s computer (ECU) has detected that the voltage in the circuit controlling the solenoid for the intake valve is higher than expected. This solenoid is crucial for adjusting the timing of the engine’s valves, affecting its performance.
P0077 quick overview
| Meaning | P0077: Intake Valve Control Solenoid Circuit High Bank 1 |
| Is it serious? | Yes, this code can lead to engine performance issues, including stalling and reduced fuel efficiency. |
| Possible causes | – Faulty wiring or connections – Damaged intake valve control solenoid – ECM/PCM issues |
| How to diagnose? | Use a scan tool with bi-directional controls to test the solenoid. Verify if PCM is properly commanding the solenoid. Check voltage drop from the control side of the solenoid to the battery ground. Test for engine RPM change by manually grounding the control wire. Inspect for shorted wiring if unexpected voltage is present. |
P0077 Meaning
When your car shows the P0077 code, it’s telling you there’s too much electricity where it shouldn’t be in the part that helps manage how the engine “breathes.” Think of it like a gate that opens and closes at the wrong speed because the signals it’s getting are too strong.
This can make your car run rough, use more gas than it should, or even stall. Fixing it usually involves checking the electrical parts for damage or bad connections and making sure everything is talking to each other the right way.
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How to fix P0077 – learn from mechanics
I looked into P0077 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.
Case #1: Hyundai P0077
Vehicle Information 2009 Hyundai Elantra SE 2.0L
Issue + Repair History
- MIL Lamp on with trouble code P0077 (CVVT Oil Control Valve circuit high)
- CVVT oil control valve replaced previously
Other OBD2 Codes + Test Results
- P0077- CVVT Oil Control Valve circuit high
- Voltage measurements:
- White wire: Battery voltage
- Blue wire (at PCM): 3.6 volts
- Blue wire (with engine idling): 12.4 volts
Mechanic Suggestions
- Use a scan tool with bi-directional controls to command the solenoid on and off.
- Verify if PCM is commanding the solenoid properly.
- Check voltage drop from control side of solenoid to battery ground.
- Test for definite engine RPM change by grounding the blue wire with engine running.
- Check for a shorted wire if voltage is present at the blue wire even when unplugged from OCV.
Final Fix
- Used a scan tool with bi-directional controls to command the solenoid on and off. After several commands, the issue was resolved.
Case #2: Ford P0077
Vehicle information
Ford Focus, 2015, 2.0L engine
Issue + repair history
- Check engine light on intermittently
- Replaced intake valve control solenoid
- Cleared codes but P0077 keeps coming back
Other OBD2 Codes + Test Results
- P0077: Intake Valve Control Solenoid Circuit High B1
- Live data shows intermittent voltage spikes
Mechanic suggestions
- Check wiring harness for any damage or corrosion
- Verify continuity and resistance in wiring
- Inspect connectors for loose connections
- Test power and ground to the solenoid
Final fix
Replaced damaged section of wiring harness leading to the intake valve control solenoid.
Case #3: Toyota P0077
Vehicle information
Toyota Camry, 2016, 2.5L engine
Issue + repair history
- Check engine light on constantly
- Replaced intake valve control solenoid
- Cleaned connectors and terminals
- Issue persists, car stalls occasionally
Other OBD2 Codes + Test Results
- P0077: Intake Valve Control Solenoid Circuit High B1
- No other codes present
- Test results show inconsistent voltage readings
Mechanic suggestions
- Perform thorough inspection of wiring harness for any breaks or shorts
- Test continuity and resistance along the entire circuit
- Check for any signs of water intrusion in connectors
- Verify proper voltage supply to the solenoid
Final fix
Discovered a loose connector pin causing intermittent contact. Repaired connector and secured pin. Cleared codes and performed road test, issue resolved.
How to diagnose P0077
I made you an overview of solving this DTC, based on all the advice that was suggested by certified mechanics to address this issue in previously mentioned service cases.
| Diagnostic Step | Brief Explanation |
|---|---|
| Use a scan tool with bi-directional controls | Commands the solenoid to turn on and off to test its operation. |
| Verify PCM commands | Checks if the car’s computer is correctly controlling the solenoid. |
| Check voltage drop | Measures if there’s a significant loss of voltage in the circuit. |
| Test for RPM change | Grounding the control wire to see if it affects engine speed, indicating solenoid response. |
| Inspect wiring for shorts | Looks for electrical faults that might cause high voltage in the circuit. |
| Check wiring harness and connections | Examines the wires and connectors for damage, corrosion, or loose parts. |
| Test power and ground to the solenoid | Ensures the solenoid is receiving the correct power supply. |
| Verify continuity and resistance in wiring | Checks for breaks or resistance in the wires that could indicate a fault. |
| Inspect for water intrusion in connectors | Looks for signs of water damage that could affect electrical connections. |
| Repair or secure connectors and pins | Fixes any found issues with connectors or wiring to ensure solid contact. |
Car Diagnostics Training
- Car Electrical basics
- OBD-II scanner basics
- How to use an OBD reader
- Introduction to a Bi-directional Scan tool
- OBD scanner buyer’s guide + discounts
I test OBD-II scanners and make DIY Engine diagnostics guides to help you solve your car problems without having to depend on the mechanic. A lot of them will try to scam you or are just no help at all. About Juraj Lukacko