What are the symptoms of the P2422 fault code?

This blog will explain the symptoms of the P2422 fault code and also answer the following questions? How to fix the P2422 fault code? How much does it cost to fix the P2422 fault code?

What are the symptoms of the P2422 fault code?

The symptoms of the P2422 fault code are given below:

  • Check engine light or EOBD in the instrument cluster 
  • Air-fuel mixture formation issues
  • Black smoke from the exhaust
  • Poor idling and fluctuations in the engine speed

The P2422 fault code means the fuel vapor purge valve is stuck, it can be stuck in the permanently open or closed position. The fuel vapor purge valve or the EVAP vent valve is actuated by the engine control unit through a PWM signal.

The engine control unit needs to alter the air-fuel mixture before actuating the purge valve. The fuel vapors in the tank are suctioned into the intake manifold and then combusted with the air-fuel mixture.

The P2422 fault code is only present on vehicles powered by petrol or gasoline engines. The fuel tanks are no longer allowed to be vented to the atmosphere, therefore manufacturers introduced fuel evaporative emissions systems. The fuel vapor purging function was added to the programming of the engine control unit.

Let’s take a closer look at each of the symptoms for the P2422 fault code:

EOBD or check engine light active in the instrument cluster.

The fault code P2422 is stored in the fault code memory of the engine control unit when the air-fuel vapor purge valve does not open or close upon actuation. The engine control unit is monitoring the percentage of oxygen in the exhaust gasses with the help of the oxygen or O2 sensors.

When the fuel vapor purge valve is open the lambda value moves towards rich or becomes less than 1. This is because the vapors are basically petrol vapor in the tank that enriches the overall mixture.

If the valve does not open then no enrichment of the mixture takes place, and the engine control unit does not detect any change in the lambda value as the fuel vapors do not enter the intake manifold.

The engine check light will turn off after the fault is rectified by replacing the faulty purge control valve. The fault code memory is erased after replacing the valve.

Air fuel mixture formation issues

The P2422 causes problems in the air-fuel mixture of the engine. Most modern petrol engines have direct electronic fuel injection. The air entering the intake manifold is determined by the pressure in the manifold and the temperature of the intake air. The engine control unit also measures the engine load from the throttle position and the engine speed.

The fuel purging only takes place when the engine speed is low and it is operating at partial throttle. The fuel injection quantity is reduced for the duration at which the fuel purge control valve remains open.

If the purge control valve is stuck close then the engine operates at a lean mixture as no fuel vapors are entering the system.

The engine control unit can also store consequential fault codes due to P2422. The status of the fault code is present and stored and it is not possible to erase the fault code until the cause is rectified.

Black smoke from the engine

Black smoke from the engine is a sign of improper fuel consumption. There are unburnt hydrocarbons present in the exhaust system due to the additional or lack of fuel vapors in the air-fuel mixture.

The black smoke can also occur intermittently when the engine control unit starts the fuel purging phase. Additional problems like soot deposits on the fuel injectors and spark plug electrodes can also occur due to P2422.

In some cases, combustion misfire takes place in multiple cylinders as the air-fuel mixture is not okay. Black smoke can also damage the components in the exhaust system like the catalytic converter and the turbocharger.

Poor idling and fluctuations in the engine speed

The fault code P2422 leads to poor idling and unstable engine speed. As the engine control unit tries to start the fuel purge phase when the engine is idling, it constantly tries to change the air-fuel ratio.

If the purge control valve is closed or there is a leak in the fuel vapor, it will cause the mixture to become lean. A lean mixture reduces the engine speed and then the engine control unit activates the anti-stall mode.

Petrol engines idle at 700-800 RPM, and the engine speed is low. As the additional fuel vapor is not entering the combustion chamber, the mixture becomes too lean and there is not enough fuel to maintain the idle RPM range.

The fluctuations will only stop after rectifying the P2422 fault code and resetting the adaptation data in the fuel control unit.

How to fix the P2422 fault code?

The procedure to diagnose and fix the P2422 fault code is as follows:

  • Perform the initial scan for the fault code by connecting the OBD II scanner.
  • Read out the actual values of the mixture formation in the engine control unit and note the lambda values
  • If the lambda values are less than 1 then the valve can be stuck open and if it is greater than 1 then the valve is stuck close.
  • Actuate the purge control valve and observe that a ticking noise must come from the valve when it is actuated by the control unit.
  • Check if the electrical lines are okay and replace the purge control valve.

One of the methods to check the cause of the P2422 is to temporarily disconnect the hose for the fuel vapor and observe the engine rpm. If they become stable then the purge control valve is stuck in the close position.

When the fault code P2422 occurs even after replacing the purge control valve then there can be a leak in the fuel vapor line. It can be identified by using a smoke machine or slowly spraying a flammable spray-like brake cleaner near the intake manifold. 

If the engine speed increases after spraying the brake cleaner then there is a leak in the evaporative emissions system. Another cause is a choked or blocked charcoal canister, replacing the canister is the only remedy.

How much does it cost to fix the P2422 fault code?

The cost to diagnose and fix the P2422 fault code is relatively inexpensive. The new purge control valve can cost 20 to 30 USD. Purge control valves are usually located on the side of the engine compartment so replacing does not require any major disassembling.

The dealership can charge 10 to 20 USD for diagnosis and replacing the faulty purge control valve.

Other articles about Vehicle Fault Codes you may be interested in

What are the symptoms of the P0715 fault code?

Why does the fault code P0400 occur in diesel cars?

What does the P500 fault code mean?


This blog explained the symptoms of the fault code P2422. It is possible to drive the air with the fault code P2422 still present in the engine control unit fault memory. However, operating the engine will lead to poor fuel consumption and a reduction in the efficiency of the catalytic converter.