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Common Problems And Fixes, Gas Mileage, Driving experience For 2004-2009 Toyota Prius

No car beats the fuel economy of the Prius, that is one of many reasons it is the best-selling hybrid. Many people are still asking how dependable Prius is in the over time? How well engineered is the hybrid technology running the car? What can an owner expect costs could be for the maintenance and repairs? We will answer all these questions and more.

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The car that changed the automotive game is the Toyota Prius. The technology is simple, yet has a certain sophistication about it that blends well into any crowd.

The car itself really is quite popular. Most people know them for fuel economy, which is great, but what about how they stack up against other cars? I know that I have compared them to other basic commuter cars, but what about the actual costs of maintenance could an owner expect on a clean second generation (2004-2009). Here is what I have found.

Fuel Economy For Toyota Prius Gen 2

What this car is best known for, great fuel economy. While the EPA (environmental protection agency) rates the 2nd generation Prius at 48 city, 45, highway, and 46 combined, I know those numbers are not true. Prius actually can do better than that. Just today driving home from Seattle I was getting close to 50 on the highway.


Other Prius owners that I have had the pleasure of chatting with have even documented record numbers in the 60 MPG range at over 300+ miles on that trip. That is super impressive. Coming it at a hefty (no sarcasm there) 11.9 gallons the fuel tank can easily get you well over 400+ miles no sweat.

So what could one expect to spend on fuel for a year on one of these? Well if you only drove an estimated 15,000 miles you should land around $1,100 dollars for fuel (give or take on current fuel costs) That is significantly less money than say a V6 Rav4 which could easily run you about twice that for the same miles driven.

When it comes to fuel costs, Prius is for sure the winner. But this is not all roses and unicorns. During the winter Prius (and any car really) will take a pretty good fuel economy hit, gas mileage drops to 38-39 MPG combined. Not awful but certainly not 50+.

Driving the Prius in snowy and icy conditions, it is very stable on the road. The weight of the hybrid battery offers stability, this can mean that the rear end does not spin out as easily. Another cool thing is that due to the size of the fuel tank, it does not take long to fill it. Although this kind of stinks when you want to wash your windows while you wait.

Even with the good and bad factored in, Prius is still a very good car for just about any condition.

Powertrain, The Prius Engine and Transmission

The Toyota 1NZ-FXE engine is very similar to the Toyota Yaris engine. It has a few modifications that allow it to operate in an Atkinson engine cycle. This means that Prius can, on demand, have a variable compression ratio. We can get more power or more economy just by phasing the camshaft. Pretty neat. The engine also has a low maintenance timing chain. Many Toyota vehicles utilized timing belts for quite some time, but after seeing the benefit of timing chain engines with improved technology, this was a no brainer.


The transaxle utilizes two electric motors called MG1 and MG2. MG2 which is also referred to as a traction motor, is the one that moves the car down the road. MG1 is both the starter motor, and it also a generator while the engine is running, this charges the traction (high voltage) battery.

The Prius Hybrid Powertrain

Initially, when you are creeping along (15-20 mph) you are running solely on electric power. This is also if the car has gone through the warm up sequence after sitting overnight. Once you hit this threshold the gas engine takes over. I have seen in my Prius with very controlled acceleration from a stop, getting up to 40 mph before the gas engine kicked in.

Stopping at a red light or stop sign, the gas engine (if not shut off already from coasting) will shut down Then when you mash the throttle again you are back in the seat with MG2 and the gas motor propelling you down the road.. During down hill decent or just coasting Prius goes into regenerative braking mode which allows it to capture energy loss and store it in the HV battery. Power flow is shown on the center display.

Sportieness Of Prius

The Prius is not out to win any autocross events, though I hear people are doing this. The ride is gently and mostly quiet, when you are in electric mode. The power and responsiveness of the MG2 motor, allows Prius to be quick off the line. Even though the car is a strange shape, it has a great turning radius and hardly and blind spots.

What The Real World Costs Are For Prius Maintenance

Prius is pretty cheap to maintain. Tires (which for best MPG, should be low rolling resistance tires) An owner could expect anywhere from $350-$475 per set, depending where they are purchased from. Brakes are lasting over 100K miles due to regen braking. Since there is no alternator or belt driven A/C compressor, the only $20 belt you need is the one that drives the engine water pump.

The engine runs on conventional 5W-30 (though synthetic is preferred for the harsh conditions we put the engine though) oil and takes 3.75 quarts.. Oil changes need to be done every 5,000 + miles, depending on your driving conditions. Air filters are not super expensive at around $15 bucks for the OEM engine air filter and $20 for a double pack of aftermarket charcoal activated cabin filters amazon, these are items that anyone can afford.

The hybrid system needs maintenance also. The Prius maintenance schedule shows changing inverter coolant at 100,000 miles and 50,000 miles after that. An Inspection of the transmission fluid every 30,000 miles is suggested but in my experience for $60 worth of fluid and 30 minutes of your time, this is a great investment every 60-100k miles. In my 2007 Prius, I changed hybrid transmission fluid at 250,000 miles, and it was awful. I had bought the car from the second owner who totally neglected it. I am sure it was never changed, ever.

The hybrid battery doesn't fail very often, but the dreaded P0A80 is a code no owner wants to see. My 2007 Prius still had the original battery when I got it, though it had failed which is why I bought it.

Replacing the traction battery at your local dealership can be expensive ($3,500-3,800 parts and labor), but there are other ways of doing it. One example, a used or remanufactured hybrid battery can be purchased from a batter re-manufacturer for around $1,500. Some owners have replaced individual battery modules (which should also include a balancing for proper battery restoration, and done by someone who knows what they are doing). The 2004-2009 Prius has 28 individual modules. Finding known good modules should come from a place like that tests and ensures quality of used modules. The battery repair should be followed with a balancing of the modules to ensure they are all working properly with each other.

Other Issues That Happen

There are a few problems that are mentioned with gen 2 Prius. In some 2004-2005 Prius, the Multi Function Display, that shows the state of charge, regen mode, electric mode, etc, can stop working altogether.


The heads up display can also go out as well. This means that your car will not tell you how fast you are going, and even worse, not log your mileage. My 2007 Prius we drove had this problem. I did a quick Google search and found that a tiny $1 capacitor on the circuit board goes bad.Toyota's fix is to replace the unit, which can be expensive, there are now simple fixes and replacement parts available. If you are hand with a soldering iron, it is not a big deal.


Even though Prius has some common issues, they are great cars. The fuel economy is what attracts most people to them. Once people see the reliability and low cost of maintenance, they become addicted to owning them. Once you go Prius, you never go back?

All in all they are great, cheap cars to own and drive. I plan on buying a few more for my personal fleet.

I hope that you have enjoyed reading about common fixes, gas mileage and driving the Toyota Prius. Check out my other story Why the first generation Prius is better than either generation Nissan Leaf.

See you in the next story where I am discussing why the Toyota Prius AWD-e is the best one yet and why car enthusiasts and average car guys loathe the Toyota Prius.

Also Watch New tech means more MPG from your Toyota Prius and Click to Subscribe to Torque News Youtube Channel for Daily Toyota Prius and Automotive News.

Peter Neilson is an automotive consultant specializing in electric cars and hybrid battery technologies. He is an automotive technology instructor at Columbia Basin College. He holds a Bachelor of Science in Automotive Service Technology from Weber State University. Peter can be reached on Linkedin and you can tweet him at The_hybrid_guy on Twitter.

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Fran (not verified)    November 14, 2019 - 7:03PM

My 2007 Prius has 262,700 miles. Her oil was changed consistently every 5,000 miles as were the tires rotated. The hybrid battery was replaced 2 years ago. Unfortunately now she needs a catalytic converter and a manifold. Too expensive at this point. Sorry to see her go but we’re buying a new 2019. Fantastic car excepting high winds or snow. I’ll miss her.

Milo (not verified)    July 6, 2021 - 2:00PM

In reply to by Fran (not verified)

A bit late as I just saw this post but I had the codes indicating a catalytic converter issue that needed replacement. I used CataClean from Amazon and the issue went away. Hope this helps others. My 2007 Prius has 280,000 miles.

connie brasher (not verified)    June 20, 2020 - 7:19PM

I am 68 and looking to but a 2005. From second hand car lot. Car looks good. Motor clean. How would I get it checked out. By a company if so who do you recommend. I am a widow so don't care to be ripped off. Being a woman.

Wogga4eva (not verified)    February 3, 2021 - 9:02PM

In reply to by connie brasher (not verified)

How did buying the used Prius go? I ask because I got one for almost nothing, due to a failed hybrid battery. I figured "I can fix this probably" - and I did.

The problem was that the car needed a lot of things that regular cars also need after many miles: brakes - rear struts - water pump - muffler - even some odd things like: gas tank straps and hood release cable.

I figured 'these are great cars' - nothing ever goes wrong , no need to check out with a 'conventional shop'. WRONG. Always check out a used car, even if you don't like to bargain based on what you learn.

Wogga4eva (not verified)    February 3, 2021 - 9:19PM

Peter: thanks for your article, which I found very helpful. I just bought an older Gen II prius and rebuilt the HV battery pack, as you suggest. While they are great cars, mine needed a lot of 'conventional car' stuff, that I didn't notice. I wish I'd had it checked out before purchase...but then I might not have bought it. I am enjoying it. If anyone does get one with a failed HV battery, don't worry too much, it's not the worst to repair yourself if you're handy and can learn from Youtube videos. As you note, a reconditioned 'aftermarket' HV battery could be purchased or even installed for $1,000 in some markets.

After I put my HV battery back in and tested it (get the paid Dr Prius app for a test), it registered 'like new', which was reassuring, if not entirely believable... My northern US winter time MPG has been poor though. This might be due to a failing 12v aux battery (very expensive OEM, but you can get a 35AH AGM u1 battery and modify it with an adapter U1 to SAE Kit...and some people say 35AH is enough for even SKS cars)...or just due to winter. I note that Peter mentions winter time MPG around 40, which is what I get when cold to short trips. If I look at my MPG once the car is warmed up (and the 12v battery brought up to normal-ish voltage) mpg is in the mid to maybe upper 40s.

Prius makes accelerating pathetically (almost) fun!

Kelsey (not verified)    March 6, 2021 - 8:40PM

Hey friend! This is quite a longshot, but what’s the capacitor you replaced for your HUD going out? This happens intermittently in mine, and I’d be soooo happy to be able to fix it. One of those longtime questions I’ve never found an answer for on Google.