Actual number of EGR operation problems

Egrs do get clogged and throw a P0401 code, Insufficient EGR Flow. A dealer will normally replace the egr cooler and the egr valve. $800-$1000.

Gen2 Prius engines from 2004-2009 did not have egr systems.

Gen3 engines from 2010-15 have an egr system. These systems typically clog around 150k miles or higher.

Gen4 engines from 2016 up have a redesigned egr system that has not been a significant problem.

The gen3 engines also have a less frequent but still serious problem with head gasket fails. While some on Priuschat believe frequent cleaning of the egr system may prevent head gasket issues (including cleaning intake manifold egr passages) others are not convinced.

Does gen3 get clogged egrs with higher mileage? Yes. Almost guaranteed. Do gen3s have more head gasket problems? Yes. In fact there is a cottage industry developing to replace head gaskets (such as Gasketmasters in California). Are head gaskets something to forget about? No. Some can ruin the engine as well. Are there quite a few diyer's cleaning their own egrs even though it is a hard job? Yes. Is there a proven correlation on gen3s? Not exactly.

 

There’s a thread here, and im a little fuzzy on the details, but I’ll try my best to recount: a guy acquired a 3rd gen from an acquaintance, it had had the head gasket fail, been replaced (without EGR cleaning), and the new head gasket also failed, within 20k miles IIRC.

The poster bought the car at this point, and soon thereafter head gasket was failing again. He was looking for info both regarding head gasket replacement and EGR cleaning.

maybe someone recalls, can track it down?

anyway: that seems to me to point to a correlation, that clogged EGR and head gasket failure go hand in hand.

 

Here we go:

Multiple blown head gaskets in 16k miles | PriusChat

 

since we mostly see cars with problems, it is impossible to know. suffice it to say that it's something you want to do asap, and hope it's not too late.

spark plugs have a 120k interval, but most who change them say the old ones look fine. many say they still look good at 160k, so i'm in hurry on that account.

 

Here's the EGR valve, EGR cooler, and EGR pipe on our 2011 when it had 124,500 miles.

Additionally, the EGR passages in the intake manifold were about 75% obstructed in the cylinder 1 and 2 positions, much less on cylinders 3, and 4.

Posted via the PriusChat mobile app.

 

I believe that my 2010 Prius maintenance manual says 120,000 miles for plugs but, in small print, says 150,000 in some states. That suggests to me that both the 120,000 and 150,000 figures are based on emission regulations, not actual plug life span. So, in my opinion, don't worry about the exact mileage and make the change when it is convenient for you.

Here is the footnote to the 120,000 recommendation:



On this forum, and on the internet in general, you read about what goes wrong and not what goes right. I remember another poster reported what you did, that an experienced hybrid mechanic, told him that head gasket failure was infrequent and EGR cleaning not worth it. He got negative comments.

A highly respected hybrid expert known to long time forum members recommended replacing the engine coolant pump as more worthwhile preventative maintenance than EGR cleaning at my 100,000 service on my 2010 Prius. Sure there is some risk. If you have the tools, time and place to do it yourself, maybe when you are replacing spark plugs, cleaning EGR circuit could give you peace of mind.

 

There was a guy here this week that blew a head gasket in two to five minutes after an overheat warning. The traditional and guaranteed way.

 

I wouldn't believe a word what a dealership said about the egr system. They don't have a clue. Especially a service writer.....

 

I'm trying to understand the picture??????????????? did I miss something?????????

 

You are welcome. I have granted the badge of "Seriously Addicted" by PC, so I suppose I am among the people who live to share my experiences to help others.

BTW: I did the preemptive cleaning of my whole EGR system @94k. I replaced the plugs at the same time, only because I had the wiper tray out, which made the plugs accessible. $40 plugs from the dealer were worth the piece of mind, and I don't plan to remove the wiper tray until I redo the EGR system cleaning at 144k.

I Posted the story + pictures in the following thread:
My Major Surgery saga on my 2013 Prius V. | PriusChat

If you are concerned about doing a big job in the cold, I would highly recommend cleaning the Intake Manifold EGR Passages ASAP. It can be done in an afternoon, and gives you a lot of protection against Head Gasket Failure (IMHO). Do the big job of the EGR + EGR Cooler + Plugs next spring.

Also Change the Engine Coolant sooner than later, and use Toyota coolant from the dealer (It doesn't cost that much more, and is better).

 

As other posters have indicated, its probably not possible to get a figure like that from anyone here, or from the Paris Autobarn; both places only see what they see. The Autobarn has seen no EGR failures in 14 years working exclusively on hybrids, but possibly has not been looking for them either.

Meanwhile, here on PriusChat, as mentioned upthread, posts are weighted toward members having car problems. It would take a serious effort at research design to try to figure out how to get an answer like you are looking for out of the information that appears on this forum. Beyond that, the emphasis on EGR here among some members has reached a point of being self-amplifying: brand new members whose engines are running funny for no reason anyone has identified yet will see all the existing EGR posts and make their first post "OMG it's my EGR isn't it??!!?", which ends up getting counted as another thread about an EGR problem, whether it is or not.

It would be very hard work to try to adjust for those effects and get you a reliable answer to the question you've asked. No one is doing it.

There are some ways to get information that's adjacent to your question.

On the EGR valve blockage data thread, we have people reporting their mileage and the EGR flow monitor test result reported by their ECM. The more people who can do that, at different mileages and with different driving conditions, the more we know. If you think you're going to dismantle and clean the system anyway, it is a great contribution if you can report your mileage and the flow test value from before and after the cleaning. Getting the test result doesn't take any time or getting your hands dirty, just plugging in any scan tool that can retrieve "mode 6" monitor results.

Besides gathering that information, there is a case to be made for physically taking your intake manifold off to inspect and clean its four small EGR passages. The ECM's flow monitor only uses one sensor and sees one overall flow result, so it isn't capable of telling you anything about what happens in the manifold where the flow splits into four, and it's possible that uneven flow there has a more plausible connection to possible head gasket damage than has been proposed for clogging further upstream. The good news is that compared to dismantling the rest of the EGR system, the intake manifold by itself can be whipped off in an easy 20 minutes or so.

 

If the rationale for the coolant change is due to spillage when cleaning the EGR circuit, it can be done without spilling, more info in first link in my signature.

 

I suggested that the OP change his coolant based on years of use. When I changed the coolant at 94k, I was surprised at the color difference between the old and new coolant. Basically changing the coolant is "low hanging fruit", since the change is pretty easy to do, and can have a pretty big impact before Winter. The EGR passages is definitely the thing to attack first.

 

Yeah, I agree, especially if scheduled engine coolant change is close. Same thing for spark plugs, and maybe PCV valve. With the latter good time to at least blow carb cleaner through it.