2012 Prius - The Good Ol' P0301 Gremlin!!!

I was thinking the same too. It is not a critical performance component. It's just a damn fastener. That stud is coming out too then and staying off!

Screw it then. I'll just take her into Gasket Masters and have them do the tests.

 

Got the '12 back together. Think I did a really good job on it. I did disconnected both batteries prior to doing the job. Good thing too since tons of coolant leaked out everywhere though all the hoses were clamped off good. Topped off the coolant tank after everything came back together. Got ready to go turn it onto to maintenance mode. Boom get the good old:

"Check Hybrid System Stop the vehicle at a Safe Place"
​

message. Dr. Prius shows I have 60% on my hybrid battery, which should be good enough. I clear the hybrid error code via Dr. Prius. Shut her down. Disconnect the hybrid battery and disconnect the 12v battery for 5 minutes to reset the codes. Upon reconnecting the batteries and starting her back up, now she turns but doesn't want to shift into gear. I am on the OG battery and the '12 hasn't ran for like a month. Good chance the 12volt battery has discharged by now. Will try to jump start her in the morning then take it from there.

Soooooo close to knowing if the EGR was the source of the issue.

 

12 volt battery checks in at 9.32vdc using my Fluke meter, measured right off the terminal posts in the back of the car. Not good enough to kick the car into gear I suppose. The current symptoms are exactly as shown in this video. Instrument panel comes on. Dummy lights stay lit. Dash panel turns on/off intermittently. Car does not shift into drive or reverse.

So here is another economic decision to make:

1. I do have a trickle charger
2. And the replacement battery is a whopping $200 bucks!

I am thinking I should put the battery on the trickle charger. That is going to take a day or two or more to resurrect the battery. But given the pace I am moving at this repair, no big deal and it does save me $200 bucks on a new battery. I can always swoop up a new battery later if the trickle charger doesn't resurrect the battery. It is the OG battery and has never been changed out. And I did notice my car making different sounds as I shut the car off prior to this repair. I am sure having it sit for a month with parasitic draws just took it all the way down.

But first thing is first, I am going to jump start her. Make sure my repairs are legit. Assess the battery situation later. Now where are my damn jumper cables?

 

Replaced EGR value. Cleaned EGR cooler with pressure washer and brake clean. Cleaned EGR pipe and intake (again) similarly. Dumped OCC.

Trickle charging has worked well for me in the past with other car batteries. Will give it a whirl. Only problem is that it takes days sometimes. I can always swoop up a new one later.

Slang for "Original Gangster" or "Original Genuine". Basically, means the original <insert blank>. In this case, it is the original battery that came with the '12 when I rolled her off the lot. Also, if you refer to a person as OG, it is a compliment of the highest order. For instance, "Mendel Leisk is the OG of the Prius Chat forums."

I couldn't find my jumper cables. So I am just going to trickle charge the 12v battery and pick things back up in a few days.

 

Also, the plan is if she shakes or not and/or the check engine lights go off or not, I will take the '12 to Gasket Masters and have them do a leakdown and compression test. Want to ensure I have no loss of power or a blown HG.

 

Haven't fired her back up just yet. I've just re-assembled everything at this point, minus the wiper assembly.

When I removed the EGR cooler, tons of coolant spilled out even though I had every hose clamped off really good. I think I used like 6-8 clamps. On some hoses, I used more than 2 clamps. There is a lot of coolant in the EGR and of course, you can't clamp off the EGR. Don't know how the guys on Youtube were able to remove the hoses with the minimal coolant spillage they showed. I think all those guys must have drained the coolant before they tackled the EGR cooler. Also, I think it is a good idea to drain the coolant before tackling the EGR especially if you are overdue with that maintenance anyway.

After I re-assembled the EGR system, intake system, I topped off the coolant and went to put her in maintenance mode and that is when I found out she wouldn't start. Aux battery is still trickle charging now. Took a reading this morning and shows the voltage is at 13.06vdc (up from 9.32vdc just yesterday). Probably good enough to re-install it at this point. But I'll wait till the trickle charger's indicator light turns green. I want to save myself the $200-$240 on a new battery, so no rush.

Oh, since coolant spilled all through the engine bay when working on the EGR, I hosed her off, used compressed air to blow out standing water, then allowed her to dry out. Batteries were all disconnected when I did this. In case I sell her, I don't want a savvy buyer to ask "Did this overheat? Why is there dry coolant all over the engine bay?"

 

Hah, genius! Mendel, you truly are the OG of the Prius Chat forums!

Yeah, I didn't disconnect the hoses from the throttle body. And I'll remember that tip in your signature for the next time I tackle the EGR valve & cooler. I read somewhere in this forum where someone said they do it every 30k miles. Given how frightening the engine shake is as a result of EGR system issues, probably a good idea to maintain that system in tip top shape at regular intervals.

Soooooooo.........the trickle charger indicator went to green! Re-installed the aux battery and re-installed the hybrid service plug. Went to turn her on and the error popped up again:

"Check Hybrid System Stop the vehicle at a Safe Place"​

I forgot to push the latch to the right after re-installing it; what a rook.

"Pro Tip": Re-installing the hybrid service plug is a 3-step process. 1) Re-insert the plug into the slot 2) Flip the latch from perpendicular position in relation to the left/right axis of the vehicle 3) Push latch to the right, if standing from the back of the car until you feel/hear a click. Otherwise, you'll get that error.​

Anyhoo, she fired right up after trickle charging the battery. But but but but but but...........she shook violently. I was pretty scared when I heard the shaking. Thoughts turned to immediately turning her off. As I reached for the ignition button, in that moment, I could hear her calming down. Then I immediately turned her back on and the shaking was no more. Perhaps it was the ECM relearning itself with the new EGR valve in that brief moment. The trickle charge saved me $200-$240 on a new battery after all.

Following Mendel's 1st link in his signature is best. But read in the spoiler what I did for my adventures in this repair.

Spoiler

I shut her down again and put her in maintenance mode so that I could ensure air pockets were driven out of the coolant system. My driveway is pretty steep, but I jacked up the front anyway to get the air pockets to bubble up. Shook her side to side to help the bubbles move through. During this process, I could hear cavitation from the water pump (I think). I left her in maintenance mode for a good 15 minutes. Inspection around the back of the car revealed what appeared to be some smoke out of the exhaust. Hard to tell though as it was still in the AM hours and it was a foggy cold morning; atypical of California weather. CEL did not turn on. Reading the DTC's with Car Scanner showed all previous DTC's were inactive. I cleared the DTC's from within Car Scanner anyway.

After some clean up, took her to go grab some KFC then headed for the freeway. Two exits later, was on the back roads on the way back home. No issues to speak up. No noticeable loss in power. No CEL reappearing. Also made sure to blast the heater to get all the air pockets out of there too. Thankfully, it is a cold day. Got home, left her running as I popped the hood. Cavitation sound was gone. Then while she was still running, very carefully loosened the coolant tank cap. Air hissed out in a gust for a brief second. No danger of eruption, so I pulled the cap completely off, then immediately re-installed the cap. I did this to allow what trapped air may have been in the coolant system to escape. Closed the hood. Then finally walked around to check the exhaust for smoke. It is now the afternoon and slightly warmer, but there was no smoke to speak of. Silly me though, as I shut her off, I failed to take note of the trip summary for miles driven and MPG. Oh well, there will be an opportunity for that in the next drive.

EDIT: I'll let her cool down and will drive her again in the evening. Before I drive her again, will mark the coolant level with a grease pen and keep an eye out on the levels.

I'll give Gasket Masters a call tomorrow to find out when I can take her in for a compression test and leakdown test or what ever test they have to ensure there was no catastrophic engine damage. Will report back then.

 

Point is, it is a good idea to perform regular maintenance on the EGR system. Agreed?

 

Ok, so here is the verdict from Gasket Masters: No apparent engine damage. No apparent head gasket failure. The caveat, there was no test performed with any instruments. Largely visual and auditory inspection. A test visually comparing piston heights of cylinders 1 & 4 and 2 & 3 at TDC using a screw driver was performed. I didn't re-install the wiper assembly, so it made it easy for the tech to get to the spark plugs to remove them to do the test. But he had to reach down to turn the engine to TDC.

Anyhow, detailed the repair described in this thread to the tech. Asked if they could perform a leakdown or compression test to confirm if I had any HG leaks or if I had engine damage. The tech there called in to ask if he could do that but strangely was told he wasn't allowed to do it. I was not asking for free work. But I am not sure why they said they wouldn't do it. So the tech told me he would do a quick check on the piston height which I described above. He told me that my coolant tank was misaligned and that I should re-seat the tank and top it off Coolant has since dropped since my last repair two days ago but that is expected as the air pockets make their way out after topping off. He told me it sounds fine and after the test confirmed none of the rods were bent. He said to watch my coolant levels and to take it in immediately if I see any drops. I asked him how much I owed him for the test. He said, "No, you're good man." I had a Mountain Mike's Pizza DoorDash'ed to him for helping me out anyway. I'll leave a good review too.

Gasket Masters in Manteca is pretty hard to find as it is not on a main road and there are no business signs from the street identifying them. Nor do they have a sign on their shop. I believe most of there business is done at the customer's site. Took a good 10 minutes of trial and error to find them. Even Waze couldn't locate them. If you ever make your way there, drive into Dutch Bros driveway till the end and make a right. Go to the last shops which are to the right just a few feet away after making the right. Gasket Masters is the shop on the middle of the last row of shops. No signs whatsoever .

 

No, never. But I had to top off the coolant because I didn't use Mendel's instructions when tackling the EGR cooler job. Tried hose clamps and coolant spilled out everywhere.