New to Prius and New used Prius 2008

You may want to try and figure out what caused the catalyst and O2 sensor to fail. There are a number of possibilities. Watch for oil consumption. You do not want to crap out the new catalyst (very expensive) because a problem still exists (such as excess blow-by, excessive oil consumption, etc.). Alternatively, the dealer may have remedied the entire problem.

Prus Gen2 gas gauges are notorious for LACKING precision. Make sure that you keep an actual log of miles elapsed since last fill-up, fill-up gallons and then calculated mpg. When I first got my 2006, the screen display was showing that it was estimating about 37mpg (while my actual calculations early-on were in the neighborhood of 42 to 43 mpg - IOW the mpg estimate was underestimating mpg by about 20%). Over time the calculated mpg has gotten much closer to the calculated mpg (for example on my recent trip, I calculated mpg as 43.6mpg on one fill-up with the multi-function-display (AKA "MFD") had estimated 42.3mpg.

My 2006 Prius generally shows voltage at cigar lighter receptacle at about 13.8v. Your battery voltage sounds low at 11.8v. Most 12v batteries have six cells which are rated for 2.2v for each cell. Thus, the battery fully charged should be about 13.2v (2.2v/cell x 6 cells). Many batteries have a voltage that is a little but higher because the charging system is usually set somewhere between 13.4v and 14.0v.

 

Blow-by. See the Ventilation of combustion gasses section (straight-forward explanation but lacking inndetail) in the following Wikipedia page: Crankcase - Wikipedia

In a modern engine, such as your Prius, the positive crankcase ventilation ("PCV") valve is used to vent blow-by (and other spoils such as unburned fuel and condensed water) to your throttle body. Once these spoils have traveled to the throttle body, they are then supposed to be burned in the engine and then passed through the exhaust system including the catalyst. See another Wikipedia page (where they discuss PCV valve and crankcase ventilation in detail) entitled "Crankcase ventilation system": Crankcase ventilation system - Wikipedia

The links set forth above should provide you with a basic understanding of the PCV issue.

 

Have your motorcycle mechanic friend test your battery (the Prius battery is a little bit larger than a motorcycle battery). Then you can decide what your next step on the battery is.

 

Your hybrid battery is getting tired. Your right in the mileage and age for the hybrid battery to show serious signs of decay.

Good mileage is only possible with a healthy hybrid battery. The G2 is a useless go kart without a healthy battery.

Start paying attention to the Energy monitor on the mfd the center screen above the radio. Keep close on on the battery charge level. I bet your in purple alot. Purple is depleted battery.

If you cant get through a drive through window without the battery tanking to purple thats stage one of battery failure.

2 things lets test it that battery and check the cars history:

test:

Find nice level light traffic road about 4 miles long. Turn off the ac and the radio. Get the car up to 60 miles an hour. Turn on cruise control. On the consumption screen there's 2 little buttons on the bottom of that screen. Bottom left says Energy thats to watch the battery charging behavior and the one on the bottom right says reset. Push that reset. That clears all previous mpg's logged.
We want to log fresh mpg history. We want to watch the Consumption screen in this test. Drive about 3 miles at 60 with cc on. Do not touch the gas. At the end of those 4 miles the Consumption screen on my 07 says 50 mpgs. Whats yours say? I bet your in the high 30's low 40's.

history:

Go to toyota.com/owners and join the service forum. have your insurance card handy as they require the cars vin. Once properly joined you can see every service event the car has seen in an authorized toyota repair center. You may see why the car was sold. #1 reason someone sells a G2 Prius is the hybrid battery needs to be replaced. Previous owner takes it to the dealer and the dealer condemns the pack hits him with a $5000 price tag to replace it and its traded in on the spot.

use the blue search forums tab up top. Search:

hybrid battery

to see what we are all going through.

PS: you need a new 12 volt battery too. Sorry.

 

@Purrus, Don't go into panic mode yet with all the doom and gloom.

You have a few things working against you right now. One, you're new to the Prius, so you haven't yet learned how to drive it to maximize your mpg. I'm not talking about going nuts with hyper-miling stuff, just normal everyday driving. Two, you're in Denver..thin, cold air. Prii hate cold.

One of the most important things that affects mpg is what kind of trips you make with the car. The first 5 minutes of the car's warmup cycle is the least efficient and gets relatively horrible mpg. Even in nice weather, my first 5 minutes shows about 23-27 mpg, sometimes even lower in colder weather. So, what kind of trips do you make, at what speed and how much idle time? Typically, running the heat at a mid to high setting will make the engine run continuously, which is also detrimental to mpg.

A brand new Toyota S46 agm battery, fully charged, should be >= 12.8 volts at the terminals. Its rating is 325 cca, but will test significantly higher.
The same battery, middle aged with normal wear and showing ~12.3 volts at the terminals after sitting in the shop for a few days tests around 400-425 cca. That is speaking from experience. A severely weak/failing 12v battery will cause a mpg drop due to the HV system trying to keep a charge on the 12v battery. I have one of those in the shop also. It reads 12.4 volts, but will not pass the tests on an electronic tester. Also shows only 200 cca capacity. I think your 11.8 is very typical of what owners get when they check the 12v voltage using the MFD. Toyota has technicians check the voltage at the beginning of every troubleshooting procedure. They specify 11-14 volts. If <11volts, they require the battery to be charged (or problem resolved) prior to troubleshooting. It would be in your best interest to actually have the 12v battery tested by a competent facility.

A Gen 2 Prius will continue to get 40+ mpg, even with an older, low capacity HV battery, as long as the battery has not gotten to the point of tripping the RTOD. Once hybrid battery codes start popping up, it causes the engine to run pretty much continuously to keep a charge on the battery.

Your car should be using 5w-30 oil. Synthetic is preferred by most owners, but not everyone uses it.

Your hiccup and jerk is not abnormal to the point of something to worry about and can be caused by a couple different items. It could be dirty components in the intake/ignition system (dirty throttle body, maf, etc). It could also be HV battery related. I've seen this hiccup/jerk occur in cars with normally aged HV batteries, and then when the HV battery is replaced, it returns to a nice, clean, crisp on/off transition.

If it's not coding out with a check engine light, I wouldn't put it at the top of my list of worries.

 

Welcome to the Prius community, and this forum.

Not sure how much of a DIY person you are, but a minor tuneup could help some with your mpg.

1. Throttle body clean
2. Mass air flow sensor clean
3. Replace engine air filter
4. Spark Plug replacement (if the service records do not show them ever being replaced)
5. Tire Pressure. Many Gen 2 owners find better fuel economy with psi in the 40-42 range.
6. Replace your transmission fluid.(if service records don't show it).
----Don't take your car to any place like Minute Lube, Big O Tires, NTB or similar. They won't change it because A) high mileage and B) Liability. They don't understand how Prius is different than a typical transmission, and may try to convince you, that you are risking yours by doing so.

All of these are easily DIY. There are plenty of youtube videos that show the how, and the tools needed.

I would also have your wheel alignment checked when it comes time to purchase new tires.

 

I’m sure whatever oil weight they used will be fine probably 5-20 but it’s imperative you check the oil level on the dipstick at least once a week as many Prius our vintage eat oil
Check the oil first thing in the am all the oil will have dripped back from the vvt filter area and will show true level. If you pull into a gas station and measure the dipstick it will show half a quart low.
Keep it at the full line always. Top it off if it ffalls below the line.
It takes exactly 3.6 quarts with new dry filter.

Many posters did not heed this advice or just never knew there car ate oil and ran out of oil and the engine blew. Lots of people. If you have the $1500 for used engine replacement disregard my advice.

Lots of posters including myself have freaked out a little over the Vsc
Traction issue. If you hit the perfect patch of slipperyness it engages
And the brakes feel like they failed. It’s very discerning and normal.
You I’ll get used to it it’s just the way the car is setup it’s a very tight little car,
Nothing wrong with the car,
I never see snow but I hear the Prius is a pain in the nice person on a slippery hill.
Very aggressive traction control the cars software will not let you over rev
The tires as it may damage the electric motors in the trans so you can’t power out of a drift in this car.