VVT Monitor Bank 1 Fail. Signs of a faulty VVT Monitor Bank 1 and its diagnostic tips. The Full meaning of VVT is Variable Valve Timing. To understand what VVT is- if the vehicle is driving with extra weight in the trunk, pulling a trailer or at higher speeds, this system is activated. The particular tool used to relay information from the VVT to the vehicle’s computer is the variable valve timing switch.

VVT Monitor Bank 1 Fail

Once activated by the variable valve timing switch, the engine of your vehicle will receive input from the ECU to advance or retard the ignition timing. This notifies the cylinder valves to open or close sooner or later. It also tells the ignition system to fire at a designated time in order to increase engine efficiency.

VVT Monitor Bank 1 Fail

The VVT solenoid runs the system while the VVT switch provides valuable feedback to the car’s computer to change the timing on the fly. The VVT switch is prone to wearing out or breaking completely. However, the symptoms of a failing VVT switch are similar to the symptoms of a VVT solenoid.

But the most common cause of failure for both the VVT switch and the VVT solenoid is a lack of basic maintenance. For example, if your oil is dirty, sludge can clog the screen on the solenoid, causing a failure.

Common Signs Of VVT Switch Failure

Below are some common signs of a bad VVT switch:

Rough engine idle

Proper ignition timing is necessary to ensure that your engine runs smoothly and efficiently. When the vehicle is under load, the VVT switch will track the engine and send information to the computer to adjust the valve timing as needed.

And when the switch is not working properly, its ability to send accurate data is compromised. However, If you notice that the engine has a rough idle, especially if the engine RPM rises and falls from 100 – 300 RPM at idle, contact a local ASE-certified technician asap.

Check Engine Light comes on

The Check Engine Light switch On anytime one of the multiple warning codes has been produced by the vehicle’s ECU. The VVT switch is an electrical tool, it is constantly monitored by your vehicle’s onboard computer. So, when it fails or is sending inaccurate data, this will alert the car’s computer to a potential problem and light up the Check Engine Light on the dashboard.

The Engine stumbles when climbing hills or under load

A faulty VVT will also cause the engine to misfire or appear to stumble when your car is loaded with extra weight, climbing hills, or when you apply quick pressure to the throttle for instant acceleration. This results due to an electrical issue with the switch and not always the switch itself.

VVT Diagnostic Tips

Searching for Tips on how to diagnose VVT? Nowadays, computerized engine management systems have made variable valve timing a practical reality for most cars. Here are the tips on how to diagnose VVT;

Variable Valve Timing: Variable valve timing has brought with it some specific issues concerning engine lubrication and diagnostics.


Fully variable valve timing can be achieved only by using computer-operated solenoids to control the intake and exhaust valve opening and closing events. Although the various combinations of valve timing events are theoretically infinite on an electronically controlled system. And its applications are limited due to issues of cost and, in some cases, reliability.

Operating Principles

Effective valve timing is very dependent upon the velocities of the intake air flowing through the ­engine’s intake ports and the exhaust gases coming out of the engine’s exhaust ports. On most naturally aspirated engines, the intake valve does not close until the piston begins moving upward on the compression stroke.

When intake air is moving slowly at lower engine speeds, the intake valve should close early to stop the piston from pushing the intake air back into the intake port and manifold. However, as intake air velocities increase with ­engine speed, the intake valve should close later to help pack more air into the cylinder.

In theory, most VVT designs start to change intake valve timing when intake air velocities start to dramatically increase at 2,500 to 3,500 rpm. Definitely, the PCM’s actual operating strategy depends largely on the engine design and the speed limitations of the engine.

Valve timing overlap is desirable at higher engine speeds. Simultaneously holding the intake and ­exhaust valves open as the engine goes from ­exhaust to intake stroke allows the engine to make use of the slight negative pressure created by ­exhaust gases exiting the exhaust port to help draw the intake charge into the cylinder.

But at lower engine speeds and gas velocities, high valve overlap produces a loping idle because of exhaust gases pushing back into the intake manifold, plus it reduces engine running compression. Know that changing the exhaust valve timing can ­create an “EGR” effect that helps reduce Nitrogen Oxide (NO) emissions in some applications.

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