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What is a VVT Engine?

  • Author :
  • TATA AIG Team
  • Published on :
  • 07/05/2024

A powerful engine is the primary requirement for ensuring your wheels keep rotating smoothly. If your engine is faulty, you will hear unusual sounds while driving, experience poor mileage, and encounter countless hiccups. One of the most important components in the engine that ensures the vehicle drives smoothly is VVT.

In this blog, we shall discuss what a car VVT is, its working, some common code errors in Variable Valve Timing (VVT), and much more.

What is VVT?

VVT full form is Variable Valve Timing. The internal combustion engine uses this system to optimise the timing of valve opening and closing events. The primary function of VVT is to improve engine performance, fuel efficiency, and emissions control by modifying the timing of the intake and exhaust valves according to the engine's operating conditions.

Traditional engines have fixed valve timing. That means they compromise between high-speed power and low-speed torque. Car VVT overcomes this limitation by allowing variable control over the valves.

Understanding Variable Valve Timing Working

Step 1: Integrated Combustion Technologies or ICT engines have intake and exhaust valves. These valves regulate the intake of air and fuel into the engine, as well as the release of exhaust gases. Traditionally, the timing of these valves is fixed. However, as said before, VVT (variable valve timing) can alter the timing based on the engine's needs.

Step 2: Next comes the role of the camshaft. Its lobes push against the valves to open them at specific intervals. In a VVT engine, the camshaft can adjust its position to change the timing of the valves opening and closing.

Step 3: The Engine Control Unit (ECU) monitors the engine's speed, load, and temperature. This data determines the optimal valve timing for current operating conditions.

Step 4: When the ECU decides the duration to adjust the valve timing, it sends a signal to actuate the VVT system. This usually involves controlling oil flow through the use of solenoids.

Step 5: The VVT system uses oil pressure to adjust the position of the camshaft. This is achieved through a device called the cam phaser. This tool rotates the camshaft slightly relative to its drive gear to advance or retard the valve timing.

Step 7: The engine's VVT increases fuel efficiency and lowers emissions at low speeds. At high speeds, it enhances power and torque to provide a better driving experience.

Step 8: Some advanced VVT systems can also control the duration and lift of the valves, not just the timing. This further refines engine performance and efficienc

Common Error Codes in Variable Valve Timing

When the ECU detects any fault in the VVT, it logs specific error codes. Let us discuss some of the common error codes.

P0010: This code signifies a problem with the 'A' Camshaft Position Actuator Circuit (Bank 1). It indicates that the ECU has detected an issue with the VVT solenoid's electrical circuit.

P0011: This code points to an 'Intake Camshaft Position Timing—Over-Advanced (Bank 1),' suggesting that the intake camshaft is positioned more advanced than the ECU has commanded.

P0012: This code means 'Intake Camshaft Position Timing - Over-Retarded (Bank 1).' It implies that the intake camshaft is positioned more retarded than the ECU's desired setting.

P0013: It is a code for 'Exhaust Camshaft Position Actuator Circuit/Open (Bank 1).' It indicates a potential fault with the exhaust camshaft actuator circuit.

P0014: This code represents 'Exhaust Camshaft Position Timing—Over-Advanced (Bank 1).' It means that the exhaust camshaft is more advanced than the ECU intends.

P0015: A code for 'Exhaust Camshaft Position Timing - Over-Retarded (Bank 1).' It suggests that the exhaust camshaft is more retarded than desired.

P0020: Indicates an issue with the 'A' Camshaft Position Actuator Circuit (Bank 2), similar to **P0010 but for the engine's second bank.

P0021: Intake Camshaft Position Timing—Over-Advanced (Bank 2),' similar to **P0011 but affecting the second bank of the engine.

P0022: This code means 'Intake Camshaft Position Timing - Over-Retarded (Bank 2).' It is the counterpart of **P0012 for the engine's second bank.

P0023: A code for 'Exhaust Camshaft Position Actuator Circuit/Open (Bank 2),' paralleling **P0013 but for Bank 2.

P0024: Represents 'Exhaust Camshaft Position Timing - Over-Advanced (Bank 2)," similar to **P0014 but for the second bank.'

P0025: It stands for 'Exhaust Camshaft Position Timing - Over-Retarded (Bank 2).' It is the Bank 2 equivalent of **P0015.

P0028: It indicates an issue with the intake valve control solenoid circuit range/performance (Bank 2).

P1349:** A code related to VVT system malfunction, which can be due to various factors, including oil flow issues.

Signs of Defective Variable Valve Timing

  • When the VVT system encounters issues, the car's computer triggers the 'Check Engine Light' as an alert.

  • A malfunctioning VVT can cause the engine to idle unevenly. This leads to vibrations and inconsistent engine speeds.

  • If the VVT fails to optimise valve timing, the engine can compensate for the inefficiency by increasing fuel consumption.

  • The engine may struggle to deliver power, especially during acceleration, due to improper valve timing adjustments by a faulty VVT.

  • A rattling or knocking sound from the engine area can indicate a VVT system that's not functioning correctly.

  • Contaminated oil can clog the VVT solenoid.

  • When the VVT doesn't adjust the timing accurately, it can cause the engine to backfire, particularly under load conditions.

  • Unstable engine revolutions per minute (RPM) can indicate a VVT system struggling to maintain optimal valve timing.

What Happens If Valve Timing Is Incorrect?

Incorrect valve timing in an engine can lead to several issues, affecting both performance and longevity. Here's what can happen:

  • If the valve timing is not set correctly, the engine may idle roughly or misfire due to improper synchronisation of valve operation with piston movements.

  • Incorrect timing can prevent the engine from reaching its full power potential. This occurs because the intake and exhaust valves may not open optimally for efficient air-fuel mixture intake and exhaust gas expulsion.

  • In interference engines, where pistons and valves share the same space at different times, mistimed valves can collide with pistons, causing bent valves, damaged pistons, or catastrophic engine failure.

  • Due to incomplete combustion, the engine will employ more fuel than necessary, contributing to increased emissions and reduced fuel economy.

  • Valves that don't close properly can cause the engine to overheat, as the heat from combustion is not effectively released.

  • Over time, incorrect valve timing can lead to premature wear of engine components, reducing the engine's overall lifespan.

Factors to Keep in Mind for Efficient Valve Timing

Here are the key factors to consider in valve timing:

Engine Speed and Load: The engine's operating speed and load significantly influence valve timing. At higher speeds, valves must open earlier and close later to allow more air-fuel mixture into the combustion chamber and more time for exhaust gases to exit.

Camshaft Profile: The size and shape of the camshaft lobes determine the valve lift and duration. A higher lift and longer duration can improve airflow but may require stronger valve springs to prevent valve float at high RPMs.

Piston Position: Valve timing must be synchronised with the piston's position in the cylinder. To maximise the air-fuel mixture, the intake valves should open just before the piston starts the intake stroke and close after it completes it.

Valve overlap appears when the intake and exhaust pipes are both open at the same time. Proper valve overlap helps scavenge the exhaust gases from the cylinder and supply it with a fresh charge, improving engine efficiency.

Fuel Type: Different fuels may require different valve timings. For instance, engines running on alternative fuels like CNG or LPG might need adjustments to the valve timing for optimal combustion.

Engine Design: The engine's overall design, including the combustion chamber's size and shape, affects the valve timing. Engineers must consider these factors to optimise the timing for each specific engine design.

Environmental Conditions: Ambient temperature and altitude can affect air density, influencing the engine's breathing. Valve timing may need to be adjusted to compensate for these environmental factors.

Emissions Regulations: Stricter emissions standards require precise valve timing to ensure complete combustion and minimise pollutants.

Desired Power Characteristics: Depending on whether the focus is on low-end torque or high-end power, valve timing can be adjusted to suit the desired power delivery of the engine.


The VVT system adjusts the timing of the engine's valve opening and closing events. This adjustment is crucial because it affects the engine's ability to 'breathe' – that is, to take in air and fuel and expel exhaust gases.

If the VVT is faulty, your car will perform poorly and may result in an unfortunate event like an accident. This is where the car insurance policy kicks in. A four-wheeler insurance policy safeguards you financially in the event of an accident, fire, theft, or calamity causing damage to your car.

If your car insurance is about to expire, it is recommended to proceed with an expired car insurance renewal. If you renew it with Tata AIG, you can get up to a 50% discount on the premium.


What is a VVT Engine?

A Variable Valve Timing engine optimises valve timing for improved performance, efficiency, and emissions by adjusting the timing of the intake and/or exhaust valves based on engine operation.

What’s the difference between VVT and VTEC?

VTEC is Honda’s specific version of VVT technology, focusing on switching between different camshaft profiles for performance gains.

Are there different types of VVT systems?

Yes, there are various VVT systems, including those that adjust intake valves, exhaust valves, or both for comprehensive control.

Can VVT engines use regular oil?

VVT engines typically require high-quality oil for optimal performance and to prevent solenoid issues.

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