Error Code P2451: What It Means & What To Do?

The evaporative control EVAP system in a vehicle captures any raw fuel that evaporates from the fuel storage system (this would be the fuel tank, fuel cap and the filler neck). This system reacts to three specific variables – the speed of the vehicle, its engine temperature and the engine load. After assessing a reading on these three, the EVAP system proceeds with storing and purging the fuel vapours it has captured, putting them back into the vehicle’s combustion process. The EVAP system is prone to changes in pressure. It is constantly relaying this information to the PCM. If the PCM senses that any particular reading for the heater pump has taken place which is outside the manufacturer's specifications for an acceptable range, the P2451 code is stored. The code P2451 is set when the PCM detects any problem with the leak detection pump control circuit.

What causes this problem with the Evaporative Emission System Switching Valve Stuck Closed?

• Evaporative emission system switching valve failure
• Open or short harness to evaporative emission system switching valve harness
• Electrical connection issue to the evaporative emission system switching valve circuit

1. Powertrain Control Module - PCM stands for powertrain control module. It is a car part, a control unit which is utilized on motor vehicles. It is generally a combined control unit, consisting of the engine control unit (ECU) and the transmission control unit (TCU).
2. Electronic Control Unit - If your automobile's check engine light remains on constantly, and never goes off, there's a good chance that your vehicle has a damaged electronic control unit. There are a lot of reasons why a car's check engine light will remain on. The most common reason is a defective ECU.
3. Diagnostic Tools - It is always advisable to use correct tools and equipment while resolving any OBD code issue as even small mistakes can lead to wrong diagnosis. Thus, always take help from a professional who has the knowledge and experience to such tools in efficient manner. Buy new quality diagnostic tools from us today!
4. Engine Control Module - There can be some engine performance issues due to faulty engine control module. If the ECM fails or has any problems it can lead to performance issues with the vehicle like misfires, hesitation, loss of power, and sometimes even decreased fuel economy.
5. EVAP Leak Detection Pump - The leak detection pump is the component that often triggers those "Check Engine" warning lights when it detects small leaks that would be hard to see. It is required under federal law as it ensures your evaporative emission system (EVAP) is functioning correctly.
6. Vapor Canister Valve - When the engine is running under certain conditions, the fuel vapors are purged from the canister and burned inside the engine. The purge valve precisely controls the amount of fuel vapor that is purged from the charcoal canister.
7. Vapor Canister Purge Solenoid - The duty cycle EVAP canister purge solenoid (DCP) regulates the rate of vapor flow from the EVAP canister to the intake manifold. The Powertrain Control Module (PCM) operates the solenoid.

It is essential to know the symptoms of an issue as only then you would be able to solve the problem. So that’s why we have listed out some major symptoms of OBD Code P2451 here:

Common Symptoms

• Check Engine Light On

Here are some ways with the help of which you will be able to correct the OBD Code P2451.

• Faulty wiring repair or replacement
• Evaporative emission system switching valve repair or replacement
• Replace the evaporative emission system switching valve harness
• It is essential to restore the evaporative emission system switching valve circuit

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Here are some steps which you should follow in order to diagnose this fault code P2451:

• Check the reading from the PCM by using an OBD-II scanner. Any other problem codes will need to be downloaded as well.
• Inspect the fuel tank as well as its sending unit for any faults and leakages and resolve the issue.
• The leak detection pump and the EVAP system wiring must also be examined and immediately replaced to resolve the issue.
• If none of these issues shed any light on the problem, the carbon canister needs to be checked, as well as its vent valve and replaced as required.
• Also check the PCM for any faults as it may have malfunctioned and may need reprogramming and replacement. Then again check if the code returns after every step of diagnosis.

Common Mistakes When Diagnosing The P2451 Code

• Many a times a lot of time is wasted to detect a leak when this code is presented before first testing for leak detection pump operation. However, evaporative emission control system constituents are sometimes restored in error when a vacuum leak is present or the fuel cap is not properly tightened.

P2450 - Evaporative Emission System Switching Valve Performance/Stuck Open