How to solve the P0086 code?

Check the connector and wiring - Check that the VVT solenoid valve connector is in good condition, with no bent or recessed pins, corrosion or water ingress. Ensure that the connector is firmly seated. Check that the wiring harness is not damaged, chafed, exposed or broken. Repair if necessary.

Voltage check - With the engine running, there must be at least 13.4 V to the battery. Backprobe the VVT solenoid valve, usually located in the cylinder head or valve cover, and check the battery voltage.

If the voltage is not correct, suspect an open circuit between the ECM and the valve. Disconnect the connector and recheck the battery voltage. If incorrect, suspect an open circuit between the ECM and the valve. Inspect wiring and repair if necessary.

If voltage is correct, suspect a ground problem. With the key off and the engine switched off, disconnect the VVT solenoid valve connector and the ECM connector. From the VVT solenoid valve connector, check both pins short to each other and short to ground. You should measure infinite resistance to ground and across the pins. If incorrect, suspect a short circuit. Repair if necessary.