Hybrid system overheat; Engine keeps dying

Just listen to me and forget about the rest.

The great thing about Priuschat advice is you can get double your moneyback at anytime. Try that at the dealer. There is a major assumption here that everyone is an advanced diy owner who is knowledgable about Prius systems.

If you ask how to diagnose a problem you are likely to be given a pathforward. It helps to detail the symptoms and to provide scanned codes.

Your 2014 Prius is one of the most complicated cars ever made. Generally they are reliable for the first 150,000 miles, less so after that point.

The 12v battery had nothing to do with an overheating message. It was clearly bad but its more likely you also have one of the two electric water pumps failing or you are losing coolant. Likely is another word for an educated guess. Knowing the specialized Prius codes is essential. Codes are more important than the voltmeter in most cases. Guessing is often a poor option but is quickly offered here.

One of the most capable and reasonably affordable full featured scanners is the Xtool A30M. Most auto supply scanners are worthless on a Prius. There are a few bluetooth based scanners that will give partial suggestions but a quality $220 or better device is far better.

Finally your first five posts are delayed for moderation. So post four more times with more detail in each post and then responses will be faster. Unfortunately the moderators here rarely clean up posts even when the posts are blatantly wrong. Even long time members like me are not allowed to edit their posts after 24 hours. So starting your own thread like you have here is often far better than reading conflicting information that can not be corrected on this forum.

 

Best comment ever.

“The great thing about Priuschat advice is you can get double your moneyback at anytime.”

 

Likely nothing to do with your hybrid system overheating issue, but: with those miles, have you ever cleaned the EGR (Exhaust Gas Recirculation) system? See first link in my signature. If you’re viewing ona phone you need to turn it landscape orientation to see signatures.

it’s the mandatory 3rd gen (and v) flea-and-tick bath. That Toyota doesn’t want to talk about.

Best done by 100k.

 

The work of trying to figure out when it's best done is still ongoing, over on the EGR blockage data thread.

There are a couple of things to consider, in addition to simply looking at the car's self-reported flow test number.

First, the intake manifold has four small EGR passages that can clog at different rates. That can lead to uneven EGR delivery between cylinders, which is a problem even though the car's overall flow self-test won't catch it. So removing just the manifold to check those passages now and then is prudent, even when the reported overall flow looks OK. And the manifold by itself is a very easy job.

Second, there is a known way the EGR valve itself can deteriorate over time, mashed ski-jump syndrome, which causes the valve to close too far, and then deliver too little EGR when it opens (because its opening amounts are figured by counting steps from where it thinks it's closed). That does show up in the overall flow test result, but it is a separate cause of low flow, different from clogging of the cooler.

So, any time the overall flow test is giving a low result, it can be important to check the valve for this condition, and not just assume that cooler clogging is the whole problem.

This valve condition can be easily checked without even removing the valve from the car, just two Phillips screws. The screws are usually stubborn, though; a simple hand impact driver (the kind bopped with an ordinary hammer) is an easy, painless way to get them loose.