Check Hybrid System after EGR fix...help!

2010 Prius. This all started with error codes P0300, P0302, P0304, P0401. The dealer wanted around $1000 to replace the EGR Valve, which didn’t include the cooler. I decided to buy all the parts and do the repair myself. I purchased a new PCV valve, EGR valve, EGR cooler, and intake manifold, and water bypass hose (dealer noted there was a small leak in it.) Armed with the YouTube videos from NutzAboutBoltz, I spent several hours replacing all the parts.

After I put everything back together and reconnecting the 12V battery, the screen showed me the dreaded Check Hybrid System message. I tried a few things I had read online: turning the car on and off 3 times. Clearing the codes and disconnecting the 12v battery for 10 minutes. Reseating the hybrid battery plug. Dr Prius now shows 2 additional codes: P2111, and P0A0F.

I can start the car. The engine will fire up. I can drive it for a short while. However, once the engine stops running, the car will continue on battery power. But the engine will not restart. Then the battery runs out of power of course. I can then clear the codes and restart the car, and the engine will start again. I put the car in PWR mode to keep the engine running longer so I could get home. The engine will stay running as long as I keep accelerating.

Does this make sense to anyone? What did I break when repairing the EGR system? I double checked all the connections and I don’t see anything disconnected.

 

All the parts were from Toyota.

 

UPDATE AT BOTTOM!

Thank you for your reply. Answers below.

It has around 200k miles. The coolant reservoir is stable. I had to add about half a gallon of the pink stuff because I pinched off the wrong hose during the EGR Cooler replacement. I did burp the system after.

Yes, I know they are cleanable as I've seen in various videos. However, I didn't have time to soak and scrub the parts. I'll probably try to recoup some of the cost by reselling them on ebay as used.

It's possible that there is a head gasket failure due to the high mileage. I didn't try any compression testing as I don't have the equipment. I'm not a mechanic, just an IT guy. When I first got the error I looked it up on various websites (including this one) and the leading fix was the EGR, so that's where I focused my efforts. The P0300-304 codes started at the same time as the P0401.

Yes, I removed the hybrid battery plug and disconnected the 12v negative cable as I always do when I service the car...just in case. I am sure the plug was re-seated fully.

Yes, the throttle body was reconnected fully. And I was able to actuate it by hand. I did clean it with some intake cleaner. I was careful to avoid getting any cleaner on the plastic parts.

Wise advice. I stopped trying when it stopped running long enough to recharge the hybrid battery. I was in panic mode because i needed the car for work the next day.[/QUOTE]


UPDATE: I took the car to the Toyota dealer yesterday. They said there was a TSB that said to update the firmware on the ECU after replacing the EGR valve. The technician tried to update the firmware but lost connection to the ECU mid-update and bricked it. They ordered a new ECU and installed it today. This completely fixed the "Check Hybrid System" error and cleared all the codes. As of right now, no codes and the engine is running well, better than ever! The dealer only charged me the standard $110 diagnostic fee and even gave me a loaner vehicle to use overnight. Thank you everyone for helping! Putting this update here in case anyone comes across this issue in the future.

 

Thank you everyone for the help. One week later and it is still running well. Hopefully this is the last major repair for a while. I really hate working on cars. But I also hate paying a lot of money for cars. So it's a catch 22.