Changing Toyota Camry Hybrid Inverter Coolant

My wife’s 2012 Toyota Camry Hybrid was due for new inverter coolant. Toyota recommends changing Toyota Camry Hybrid inverter coolant every 150,000 miles. The process is very simple, but there is one issue: you must be able to turn on the inverter pump during the process.

Controlling the Inverter Pump

If you bring your car to a Toyota mechanic, they will use Techstream or similar software to turn on the inverter pump. Changing Toyota Camry hybrid inverter coolant at the dealer costs anywhere from $130 to $300, depending. Technically speaking, you would have to buy a license for this, which costs $3,995.

Personally, I think this is highway robbery, when all I want to do is turn on a pump to perform some recommended maintenance on my car. For purely informational purposes, I’m going to describe a workaround. You need a TechStream cable. Amazon is full of knockoff TechStream cables which are all a little bit sketchy, but should be reliable enough to perform one-time maintenance. The exact $28 cable I purchased is no longer available, but they’re all similar.

They also all include some kind of pirated version of the TechStream software. You’ll have to find that on your own, as I’m not comfortable linking to it from here. Officially speaking, I encourage legitimately purchasing TechStream…

If you can’t get TechStream going, you’re likely better off having this maintenance done at a shop.

Other Supplies Required


Zerex aftermarket coolant worked fine

You will also need coolant for your car. I went with premixed Zerex asian formula coolant (pink). You can certainly go with OEM Toyota if you prefer, but it costs more and must be purchased at a dealer. The inverter system needs a little over 3 quarts of fluid, so a single gallon should be sufficient.

10mm Allen Socket

You need a 10mm allen key or socket

You also need a 10mm allen socket or key. I strongly prefer the socket.

Test TechStream

Plug in Cable

Plug in the TechStream cable to your vehicle’s OBD port

Accessory Mode

Make sure the car is in accessory mode

Before draining any coolant, make sure you can enable the inverter pump via computer control. If you can’t, you can still drive it to a shop. To start, plug the TechStream cable in to your vehicle’s OBD port, with the other end going to the USB port on your laptop. Start the car in accessory mode, without the engine running. You do not want or need the engine running for this job, but you do want the electronics to come on.

TechStream Loading

TechStream loading up

Select Vehicle

Select your vehicle

Launch TechStream on your laptop and select your vehicle year and model.

Hybrid Control

Select Hybrid Control when you are connected

Active Test

Active test is what lets you turn on the inverter pump

Once you are connected, you should see the screen shown. You want to select “Hybrid Control”. After that, go to “Active Test”.

Turn On Pump

Select Activate the (Inverter) Water Pump and click OK

Finally, select “Activate the (Inverter) Water Pump” and click OK. You should hear the inverter pump turn on. If this all worked, you’re ready to actually perform the maintenance. Turn the car off to turn off the pump before proceeding.

Draining the Coolant

Coolant Reservoir

This is the inverter coolant reservoir


Uncap it to drain faster

Now we get to the easy part. First, get the car on jack stands, ramps, or any other safe way to elevate the front of it, just like you would do for an oil change. This is the inverter coolant reservoir, labelled on the top. Go ahead and remove the fill cap on the reservoir.

Drain Plug

This drain plug needs a 10mm allen key

Here is the drain plug. It requires a 10mm allen key, as mentioned earlier.


Drain the old coolant

With your favorite bucket in place, go ahead and remove the drain plug. Get coolant everywhere, it’s all part of the fun.



This job is done

Reinstall the drain plug and pour fresh coolant into the system. Once it’s mostly topped off, go ahead and use TechStream to turn on the inverter pump. Let it run for about 60 seconds or so. Once all the air has been purged, the pump will make a different noise. Shut the car (and therefore the pump) off and top the coolant off to the full mark. And with that, the job is done.

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7 months ago

You could have saved your time and money by simply putting the car in “maintenance mode” that would turn the inverter pump on so that you can replace the inverter coolant