Gas Gauge

More than likely your check engine light is possibly a code for the catalyst below threshold and the low tire light is normal so you replace the TPMS sensors etc and so on most people don't bother but some do. If you get a reasonable scanner you will be able to read the codes that probably have your light on the check engine light that is

You may be in an East Coast area that doesn't require emissions testing and if so that check engine light won't cause you any trouble I don't know where in the East Coast you are

The gas gauge is generally related to the CM monitor display or a gas tank sending unit issue You need to keep an eye on it if you fill the car up within a minute or two does it show you have a full tank? If so it's somewhat working you can't replace the fuel level sender or the fuel pump or any of that stuff you change the whole tank and that's the only way you can do it in the United States anyway.

 

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Diagnosing the fuel gauge involves removing the rear seat base and measuring the resistance of the fuel tank level sensor.

It's not uncommon to have the sensor "wear out" and cause a false empty reading on the dash.

Do you have a digital multimeter (DMM) to do electrical checks?

IF the sensor is faulty, then the only repair is to replace the entire fuel tank assembly. Toyota designed the US - spec Generation 2 Prius with a sealed tank. There is no practical means to service the level sensor or fuel pump & filter separately.

To pursue the check engine light requires some form of capable scantool. Most generic devices can only pull codes and some data from the engine computer (ECM).

Many who own a Prius prefer to have a tool that can check all systems on the car for codes and data. Here is a thread that reviews several apps and devices that turn a smartphone into a scantool.

https://priuschat.com/index.php?posts/3290690

Posted via the PriusChat mobile app.

 

I've really got to get on finding two tanks like out of Australia and get them sent here to have on hand that will be a great thing to be able to move those from car to car as the funny business happens although quite interestingly enough knock on wood haven't seen any of this except only when related to the CM monitor pumps and level senders seem to be reasonably okay in all four that we have here. But having a gas tank that would allow me access to that plate in the back to actually get to the pump like in my Corolla would be a wonderful thing given how long we keep cars My AE11 Corolla has had one fuel pump and 579,000 mi