p0455 code – meaning, causes, symptoms (& how to fix it)

p0455 is a trouble code that appears in your engine control unit when it detects a leak in the evap emission system.

there could be many different reasons for this. here is everything you have to know about the p0455 code.

p0455 definition

evap system leak detected (large leak)

what does the p0455 mean?

a p0455 code means that there is a leak in the evap emission system.

the evap emission system is a sealed fuel gas system, which is then going through your car engine because of environmental purposes. if the engine control unit recognizes a leak there, it will be stored as a p0455 code.

this trouble code is very similar to the p0442 code, except this code tells us that it found a big leak, instead of a small leak.

p0455 symptoms

you will most likely not experience any symptoms of a p0445 code other than the check engine light.

• strong gasoline smell.
• check engine light turns on.
• probably, a slight decline in fuel efficiency.

how serious is the p0455 code?

very low – there is no danger for your engine to keep driving with the p0455 code.

the only thing that could happen in rare situations is that your engine might run slightly leaner than usual because of the leak. it is also bad for the environment.

causes of the p0455 code

the most common cause of a p0455 code is that you let your car engine run at the gas station with the fuel cap removed. it can also be a leaking fuel cap or a broken hose.

• defective bleed and vent control valves.
• damaged gas cap.
• a leak in the charcoal canister leak.
• leaking evap hoses.
• leaks in the main fuel tanks.

what repairs can fix the p0455 code?

• tightening the gas cap & remove the trouble code.
• replace gas cap
• replace evap control valve
• replace evap hoses
• replacing charcoal canister
• replace fuel tank

common p0455 diagnostic mistakes

the most common diagnostic mistake for the p0455 trouble code is to start a deep diagnostic. usually, this trouble code appears when you didn’t shut off your car while refueling it at the gas station or a faulty gas cap. these are two super simple things you should check before starting diagnosing your car.

recommended tools for diagnosis

• diagnostic obd scan tool
• multimeter
• basic hand tools
• evap smoke machine
• auto repair manual
• electrical contact cleaner

how to diagnose the p0455 code

1. connect your obd2 scanner and check for related trouble codes. make sure the trouble code is not stored by mistake after refueling.
2. make sure the gas cap is tightened, and the sealings look fine.
3. check the evap solenoid. check the function by sending power to it. make sure it is sealed when it’s closed. check the wirings to it and make sure the engine control unit sends + and – to it.
4. remove the fuel vent line and pressurize it towards the tank. it should be sealed, and if you notice a leak, you can use an evap smoke machine to put smoke into it to find the leak easily.
5. if everything is sealed and the solenoid works, you can now remove the trouble codes and test the car.

related posts:

• p0442 code: evap system leak detected (small leak)
• p0440 code: evaporative emission control system malfunction
• p0445 code: evaporative emission control system – purge control valve circuit shorted

estimated cost of repair

here are some examples of the repair costs of the p0455 code. the prices include parts and labor. it does not include diagnosis costs.

• gas cap replacement cost – 30$ – 80$
• vacuum hose replacement – 5$ – 50$
• replace evap control valve – 40$ – 60$

common p0455 related questions