Toyota Tacoma P0451: EVAP Pressure Sensor → Range/Performance

Similar to all OBD-II codes P0451 It is the same for all cars.  This means your vehicle is able to be identified by the symbol. Toyota Tacoma‘s EVAP system has a pressure sensor that is malfunctioning in some way. 

The most common causes of P0451 are a bad EVAP Pressure Sensor, a clogged Fuel Tank Relief Val, EVAP Lines, EVAP Wiring, or a bad Fuel Cap.  You may also have other reasons.  We’ll cover those directly below.

P0451 is usually caused by either a bad EVAP pressure sensor, a clogged fuel tank relief valve, EVAP lines, EVAP wiring, or a bad fuel cap….

Tacoma P0451 Symptoms

In general, the P0451 won't have any effect on how your Tacoma operates or drives.  Fuel mileage It is possible that some people may feel a bit of pain, although it's not likely to be severe. Service engine light will soon be on You will get one.  The slightest change may be noticeable. The smell of gas. 

If you have other EVAP trouble codes, focus on these first to see if they help.

Toyota Tacoma Causes P0451

Below are some common reasons for P0451.

Bad/Missing Fuel Cap

To diagnose P0451, the easiest way to begin is by looking at your fuel cap.  Since a missing, bad, or under-tightened fuel cap can make your Tacoma throw this code it’s a great place to start.

If you’ve gotten a “tighten fuel cap” message recently, but the cap was already tight, that’s a strong indication that there could be something wrong with the fuel cap.

The rubber seal that surrounds fuel caps is where it comes in contact with the fuel receiver.  This seal should not be missing or dry rotted.  It should be replaced if it becomes damaged. New gas cap This could be the solution you are looking for to your problem.  However, fuel caps are often mistakenly attributed to the cause of P0451.

EVAP Lines and Wiring

Next, check the EVAP lines and hoses to see if there is any P0451 issues in your Tacoma.  Be aware of where these connect to another part, be near the exhaust or contact anything that may slowly cut through it. 

The same principle would apply to checking the wiring harness.  The first thing you would do is check for damage.  You should pay particular attention where the plug connects to the EVAP pressure sensor.  The harness may need to be replaced if the plug appears loose or damaged.

It is possible that the carbon canister might be dangerous.

Bad Pressure Sensor for EVAP

It's a perfect time to test the fuel pressure sensor.  You’ll need a good scanner.  You’ll want to test to see if it is within the specs that Toyota requires before getting a new one.  Here’s a fantastic video on how to do just that:

Oil Tank Pressure Relief Valve

Even if everything looks good, it's worth doing a test of the fuel tank pressure relief device before I make any final recommendations.  It is often difficult to access them.  Here’s a link to a great video on how to Find the source of the leak if you don’t have a smoke machine.

Conclusion: Toyota Tacoma P0451

Finding P0451 is not always easy.  The good news is that if that’s the only code that your Tacoma has, it shouldn’t really be a breakdown risk.

Please leave comments below if you have any suggestions.  We wish you all the best!