A very common trouble code with the Toyota Mirai is P0442 . This code references a number that is given to you when you plug your vehicle into a OBDII scanner, and has to do with the emissions system. It’s typically not going to be a problem that’ll lead to an immediate breakdown, but it can be annoying and cause your Mirai to fail emissions testing.
P0442: Evaporative Emission System → Leak Detected
Toyota Mirai P0442 Code Symptoms
The P0442 code on a Toyota Mirai will often be thrown after the engine has a hard time starting after refueling. I’ve personally had this problem happen to me. You’ll fill up the vehicle and it just won’t start. Then, it’ll either start on the second try or after cranking the engine for a while.
If you’re old enough to have driven a carbureted vehicle, the old stomp the gas and crank the engine method does actually help start the Mirai.
Other than the difficulty in starting, the P0442 doesn’t seem to cause any other problems (at least in the short-term). You may also smell gas when driving.
Toyota Mirai P0442 Code Defined
P0442 is a general OBDII trouble code, which means it has the same meaning regardless of who manufactured the vehicle. The code technically stands for:
Evaporative Emission System | Leak Detected
The EVAP system captures all fuel vapor from the fuel tank and sends them to the engine’s intake in order to be ignited in the normal combustion process.
When the Toyota Mirai’s computer detects that the EVAP system is not holding any pressure, it will throw the P0442 code.
Toyota Mirai P0442 Causes
There are many things that can cause the P0442 trouble code on the Toyota Mirai. The most common problem is far and away the first one listed below.
- EVAP Canister Purge Valve– The most common culprit with the P0442 trouble code and the Toyota Mirai is going to be the vapor canister purge valve. When it goes bad, it typically causes issues with the vehicle’s idle speed. This is especially true right after you fuel up.It’s really easy to replace. There are a few clips that you need to find and remove. There’s a great YouTube video on diagnosing the problem below, as well as how to replace the part. It’s fantastic. This is almost always the problem. They are really cheap on Amazon too. Always make sure to verify the fit for your vehicle. There’s a tool to check the fit right there.
- Fuel Vapor Hose– A leak in the fuel vapor hose that leads from the fuel tank to the intake will definitely throw P0442 in your Mirai.
- Gas Cap Bad– A bad fuel cap can cause the P0442 code to be thrown for sure. The Mirai will typically be warning you to tighten the fuel cap. This is a great place to start. It’s a simple thing to fix and only takes a few minutes to swap a gas cap.
- Loose Gas Cap– A loose gas cap will also trigger this trouble code. So if it’s the first time that you have experienced this issue, you may want to go ahead and tighten the cap and see if the code clears itself. Just be aware that it may take the engine several cycles clear the code.
- Fuel Tank Pressure Sensor– If the fuel tank pressure sensor has gone bad, it can cause all sorts of problems, including the P0442 code.
Good luck figuring out what is wrong with your Mirai. If there are any inaccuracies, or anything that you feel could improve the article, please feel free to comment or message. Thank you.