2012 used Prius rough idle and driving at slower speeds

But they never cleaned out the old manifold or the EGR cooler (which is sometimes called "pipe," and not to be confused with the much simpler, smaller pipe that connects the EGR valve to the manifold)? Cleaning the manifold is a relatively easy do-it-yourself project.

What's the code? You need to find out what it's telling you before clearing it.

You can find numerous related threads on Priuschat from people with similar issues.

 

watch

 

Sometimes it seems head gasket issues on these engines deserve a casket.

1. How do you know a head gasket job was done?
2. Who was the car seller? A Toyota dealer or a private party?
3. Has it lost any coolant from the passenger side reservoir?

$2300 must be a new intake, egr valve and egr cooler. A stuck open egr valve might cause some of your issues. But that kind of error is opposite of the normal Prius egr problem, eg the egr system clogs up.

The head gasket might still be the problem. If the seller told you it was replaced, there is 98% certainty the engine had a head gasket problem. They are common on this engine. If it was "fixed" it may have been a poor diy job or sealant was added to the coolant, a temporary fix.

Concerning the egr, check out The Car Care Nut youtube channel. He has an egr video showing how to check for a sticking egr valve by temporarily blocking the egr tube. It is quick and easy and could verify the dealer diagnosis. Don't expect a dealer to do the check.

So it may be time to find an independent hybrid mechanic in your area. Often an independent will save you 1/3 to 1/2 over a dealer. Sometimes the right guy with hybrid experience can more accurately diagnose than your average dealer mechanic.

Finally, at a dealer you generally talk to a service advisor, not the mechanic. Often the service advisor is on commission and is typically not a trained mechanic. It is very possible to get upsold by a service advisor with minimal technical background. Find an independent with Toyota hybrid experience.

 

Its Gasket not Casket. The quality of the gasket is not the issue; often the job is done incorrectly. Sometimes there are warped or bent assemblies. A private seller is suspect.

So did your husband do the egr blocking check?

That code is MAF which is often still defective when not replaced with oem Toyota. Sometimes the original oem is better than the new aftermarket part. Still think you need an independent mechanic.

 

P0301 indicates cylinder one “misfire”, which is very common with 3rd gen Prius head gasket failure; the failures are almost always at cylinder one, or two.

Leak down test and boroscope inspection is the usual course to determine head gasket integrity.

I would determine what’s going on with the head gasket first, resolve as needed, and immediately thereafter clean the complete EGR system, including the intake manifold.

more info in my signature. If you’re on a phone, turn it landscape to see signature.

Ok, see the code was P0101. There's probably some worthwhile in the above, but I'll strike it out. Ugh...: between the "possible" head gasket issues, hybrid battery warnings, I think you've got yourself a Toyota lemon. Or two? The amount you're spending on those rivals me and the missus' dental expenses this year.

 

Thanks for coming back with your solution.
For me it's the first time when I read about harmonic balancer and rough idle and driving at lower speeds.
Good to know.