Chevy HHR P0451: EVAP Pressure Sensor → Range/Performance

Similar to all OBD-II codes P0451 It is the same for all cars.  The following means: Chevy HHR‘s EVAP system has a pressure sensor that is malfunctioning in some way. 

A bad EVAP sensor, a clogged tank relief valve or fuel lines can cause P0451.  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….

HHR P0451 Symptoms

P0451 won't usually affect how your HHR drives or runs.  Fuel mileage It is possible that some people may feel a little bit of pain, although it's not likely to be severe. Soon, service engine will be lit You will get one.  It is possible to also feel the slight Smells like gas. 

If you have other trouble codes relating to EVAP, focus on these first and then see if this helps.

Chevy HHR - P0451

Below are some common reasons for P0451.

Bad/Missing Capacity for Fuel

It is easiest to diagnose P0451 by inspecting the fuel cap.  Since a missing, bad, or under-tightened fuel cap can make your HHR 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.

A rubber seal is placed around fuel caps to prevent them from coming into contact with fuel receivers.  You should ensure that the seal isn't dry-rotted or broken.  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 your EVAP lines and hoses to see if you have P0451 problems in your HHR.  You should pay attention to where they are connected to other things, near exhausts, and touch any object that might slowly cut through them. 

The same principle would apply to checking the wiring harness.  It should be checked to make sure it is not damaged.  It is important to pay attention to how it connects with the EVAP sensor.  It is possible to have the plug replaced if it appears damaged or loose.

Also, the carbon canister may be harmful.

Poor EVAP Pressure Sensitor

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

Oil Tank Pressure Relief Valve

After everything is in order, I'd recommend a smoke test to check the fuel tank pressure relief valve.  These are often difficult to reach.  Here’s a link to a great video on how to Locate a leak if you don’t have a smoke machine.

Conclusion: P0451 Chevy HHR

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

Please leave comments below if you have any suggestions.  You are welcome!