Just cleaned EGR and Manifold on my 2010

What's the miles?

 

Read posts #1, #6, #40, and more in this long thread:https://priuschat.com/index.php?posts/2884348

 

Don't be surprised if the "other thing" comes along soon (head gasket failure). My 2 cents:

The engine's wellbeing depends on the EGR system behaving as it was when it rolled out of the factory. Judging from the rate it accumulates carbon, and considering how onerous the cleaning is, I'd recommend every 50K miles.

At 171K miles, the engine's been running for a protracted time with insufficiently cooled exhaust gas, reduced flow, possible damaged EGR valve, and last but not least: an asymmetrical reduction in EGR gas supply, with the cylinder one end being the most clogged.

Is coolant level stable in the reservoir?
Have you had engine shaking on cold starts, particularly after sitting overnight?

 

Readme.

 

Yeah I don't think Toyota saw this coming, and now it seems like they just want all the customers to "go away". Not atypical for car companies now.

Mercifully it's possible to get the EGR components out, and there are a few tricks. For sure take the wipers and cowl off; heck you have to do that for just the spark plugs. A couple more tips:

1. Remove the EGR cooler lower nut, at least. And leave it off permanently. Better: remove the stud there too, because then you can extract the cooler without removing the two rearmost studs, at the exhaust manifold connection. Side benefit: the gasket at the exhaust mainifold will hang up on those studs, not drop down, never to been again. And when reinstalling the studs will retain/align the gasket. Note: that lower cooler bracket stud will likely be very stubborn; it took me at least 15 stressful minutes backing it out, one click at a time with a dimnutive 1/4" wrench, one-click at a time (due to all the adjacent stuff), fearing I was going to round it off.

2. To avoid virtually all coolant spillage, before doing anything drain 2 quarts or liters of coolant from the radiator drain. This will drop the level below the EGR system, apart from a little trapped at the back corner of the cooler. When everything is done just pour it back into the reservoir. With a 2010 you'll have the engine coolant vent (white cap on black plastic coolant junction, just above EGR components). Leave it open while pouring the coolant back in, and squeeze the coolant hoses as you go. When coolant starts coming out of the vent close it. Coolant will end up slightly higer in reservoir, will settle down with a few days drving.

More details, info, links in top two links in my signature. On a phone turn it landscape to see signatures.

All that said, there's still a risk the head gasket is going to let go soon, or it's started; boroscope inspection of the interior of the four cylinders can help diagnose that.

For the P0401, maybe the EGR valve has sustained damage. The EGR cooler (colloquial name, Toyota calls it "Pipe) name is called cooler for a reason: it's interanal radiator is supposed to cool the exahust gas passing through. Carbon coating acts like an insulator, reducing it's efficacy. Just downstream is the EGR valve, which contains an inverted plastic bucket with a small ramp and stop. This latter can develop a groove, perhaps from overheating, and then not function properly. With flow reduced by carbon build up the valve may also be going through more up/down travel, to compensate? Anway, deffective valve might be the cause of the code.

 

A 401 can be caused by flow at low rpm’s when the egr valve is shut, by egr pipe leaks or by a complete egr cooler clog. The car is automatically testing for those conditions which creates the code.

The Techstream egr step test described in the links above makes it easy to determine if your 401 is a sticking valve or a clogged egr system.

Toyota knew they had various engine problems and released several revised parts and updated ecm code. One was a revised egr valve.

 

OP reports everything was cleaned though.

 

Clean does nothing for sticking valves or leaks.

 

Very important! Did you check the waterpump for any type of tension from impeller?