Hi all! Thanks in advance for your help. I have a 2006 Prius that’s been having what I thought were braking issues. I don’t know a lot about cars so please excuse the somewhat limited description of the issue I can provide. But everytime I brake, the car has been really slow/jolt-y to brake. As of yesterday, there’s also been a shudder everytime I come to a stop. I took it into a mechanic this week who said the brakes are fine and though they don’t know a lot about Priuses, the best description of the problem/guess they could give me is that something weird is happening where the car is switching from some kind of hybrid to manual mode, which is why I’m feeling that weird jerkiness/jolt. I don’t know a lot about cars so I’m really worried this could potentially be a larger issue with the engine. Can anyone help troubleshoot what might be happening, and if possible please explain in layman’s terms? If it helps, I’m due for an oil change here soon and I’m not sure if that’s what’s causing this. Thanks again for your help!
No codes, I need to check the oil level but I do know I’m due for an oil change and I’m getting that done tomorrow.
These cars tend to burn a lot of oil as they age, as much as 1 quart per 1000 miles or more. So if you are waiting until 5000 miles to change your oil, you could have very little oil left in the engine. This car does have somewhat of a non smooth transition from hybrid power to engine power. But if you've had this car long enough, you would have noticed that. It wouldn't be something new
So are you thinking the experience I’m having is probably due to being low on oil. If so, will the car likely go back to normal once I get the oil change? Also, let’s say I get the oil change and the car starts driving normally again…is there any long-term damage that I need to worry about? Or will I likely be good to go once the oil change happens?
oil change doesn't really fix any problems. You can check if you have low oil by pulling the oil dipstick, wipe it clean, insert it and pull it back out for a reading. You should be doing this every 1000 miles and add as needed
When was the last time you had a brake service, or brake fluid replacement? Toyota USA very vaguely recommends a more in-depth brake inspection every 30k miles or tri-yearly. They’re silent on brake fluid replacement, but Toyota Canada recommends to replace every 48k kms (~30k miles) or tri-yearly. I had an experience with a previous car, “professional” brake fluid replacement left it with one rear drum brake disabled, experienced reduced brake effectiveness, and an odd side-to-side rocking just as car came to a stop. Just for giggles try raising rear of car, spinning wheels while someone applies brakes?
Oil level will not cause this situation unless it has been run very low on oil for so long the engine is close to dead. Your knowledge and technical understanding make it impossible to diagnose from here. Many will share their experiences, which may or may not help. I will take your mechanic's statement as the most useful observation, given he is a mechanic and knows stuff. There could be a possibility the engine is running poorly and when coming to a stop is misfiring a bit. I doubt it is the transmission, they are pretty bulletproof. Go back to your mechanic, ask him to check fluid level in the transaxle. If low replace only with toyota stuff, this is a unique design and best to use their exact fluid. Also ask them to look at and possible replace the spark plugs, air filter, and clean the MAP sensor. The coil packs may also be starting to fail so they could be put on the list too. If you have service history on any of this or the mechanic says they look new obviously don't bother replacing them. Since he says the brakes are fine, leave them but consider having the fluid bled out and fresh fluid in the system. The metric for this is percentage of water in the fluid, an easy to test measurement. For now I would advise skipping this, it is more of a longevity service item and putting it off until the car runs right is not a problem.
