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P0450 OBD-II Trouble Code: Evaporative Emission Control System Pressure Sensor Malfunction

Check Engine Light

Diagnostic Trouble Code (DTC): P0450

P0450 code definition

If a vehicle has stored a P0450 code, it means there has been a malfunction with the evaporative emission control system pressure sensor.

What the P0450 code means

The evaporative control EVAP system in a vehicle is responsible for capturing any raw fuel that evaporates from the fuel storage system (this would be the fuel tank, fuel cap and the filler neck). This system is designed to react to three specific variables – namely the speed of the vehicle, its engine temperature and the engine load. After assessing a reading on these three, the EVAP system can proceed with storing and purging the fuel vapors it has captured, putting them back into the vehicle’s combustion process.

As you can imagine, the EVAP system is prone to changes in pressure. It is constantly relaying this information to the PCM (Powertrain Control Module). If the PCM senses that a pressure change has taken place which is below the manufacturer's specifications for an acceptable range, the P0450 code is stored.

What causes the P0450 code?

There are three main reasons that a vehicle would store this problem code:

  • The EVAP pressure sensor malfunctioned and gave the PCM a faulty reading
  • The EVAP pressure sensor is suffering from a poor electrical connection
  • The EVAP pressure sensor harness is shorted or open

Of course, it’s also worth considering that the PCM is simply not working correctly. This is pretty rare, but if none of the three seem to be responsible, you’ll want to look into the possibility.

What are the symptoms of the P0450 code?

Unfortunately, there aren’t any noticeable symptoms that are associated with the P0450 code. Therefore, if the Check Engine Light fails to come on right away, it could be a while before the driver figures out something is wrong.

That being said, sometimes, they’ll notice a fuel odor. This is being caused by the release of fuel vapors the EVAP system is failing to retrieve.

How does a mechanic diagnose the P0450 code?

Due to the lack of symptoms that go along with a P0450 code, a mechanic will need to do the following to get an accurate diagnosis:

  • Get a reading from the PCM by using an OBD-II scanner. Any other problem codes will need to be downloaded as well.
  • Then, they’ll need to inspect the fuel tank as well as its sending unit.
  • The pressure sensor and the EVAP’s system’s wiring must also be examined.
  • If none of these issues shed any light on the problem, the carbon canister will need to be checked, as well as its vent valve.

Common mistakes when diagnosing the P0450 code

Sometimes, the problem is as simple as a faulty fuel cap. This is an easy and affordable fix, so much so that it often doesn’t get considered at all. The same goes for the purge and vent valves of the EVAP system. Again, these can be extremely easy fixes that clear the code and don’t cost much, so they definitely need to be addressed.

How serious is the P0450 code?

It’s not a dangerous problem, but it does mean that the vehicle’s engine is working sub-optimally, which is never the type of issue you want to leave for long. As we’ve explained above, the underlying source is often a pretty easy fix too, so there’s no reason to let this one persist long enough to cause something worse.

What repairs can fix the P0450 code?

Common repairs include:

  • Replacing or repairing faulty wiring
  • Replacing or repairing the EVAP pressure sensor
  • Replacing or repairing the fuel cap
  • Replacing or repairing faulty EVAP valves

Additional comments for consideration regarding the P0450 code

Although this problem isn’t nearly as bad as others represented by their own trouble codes, it should be fixed right away to avoid further damage. Make sure any related-trouble codes are investigated too.

Need help with a P3440 code?

YourMechanic will actually send a certified mobile mechanic to your home or place of business to assess and repair your vehicle. We’re happy to provide you a quote upfront or schedule an appointment online to learn more about our services. We also invite you to speak with a service advisor by calling us at 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
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