2006 Prius P0453, P0171 drives fine bad fuel economy help??

2006 Prius Gen 2, 218k miles, P0453, P0171 codes.


I have another thread on here for several other issues, I’ve had this Prius since March 2019, and I’ve had to end up doing a LOT more work than anticipated.

Recently without warning the vehicle ran low on oil without ever giving any other kind of indicator, and the bearings shaved off and the motor needed to be replaced or rebuilt. Luckily I knew a great mechanic guy with some other priuses used for parts, and he cut me an EXCELLENT deal on replacing the motor and transmission from another 2006 Prius with only 138k miles on Both.


Since that repair, the car has been throwing P0453 and P0171 and the fuel economy averages 35-37mpg. Occasionally the hybrid battery codes pop up, but I clear them and they stay gone for the rest of that trip.


Took it back to the mechanic and he replaced the tank pressure sensor, and one other sensor, and suggests we take it to Toyota for an in depth diagnoses ($150-$200) and then repair...

from my research the only other option could be the fuel pump.

Can the fuel pump be replaced without replacing the entire fuel tank?


The car drives and runs fine I got it up to 100mph testing the new motor and transmission, and it’s smooth and drives great, it’s just these darn codes and the very very BAD gas mileage.


I could really use some help on this one quickly lol, I can’t afford to pour any more massive funds into this, especially during the holidays. This car has been most of the time I’ve owned it either in the shop or being worked on by me. At this point I could have bought a used newer model and paid cash...


Here’s the link to my other thread that shows the majority of what’s been replaced:



2006 Prius codes P0420, 0171, 1121, and more rebuilt battery | Page 2 | PriusChat


Thanks for any help or advice!

 

Thanks! I’m not sure about the air intake system, EFI M relay, or the PCV valve.
but everything else on your list has been replaced, recently the fuel rail and injectors as well as the actual engine and transmission were replaced because the bearings grinded off causing engine issues, and I got a good deal on a used engine and Transmission.
Then in December, I went ahead and had Toyota Test it with their diagnostic and they said it was the vapor canister and the clips, which was just as easy to replace the entire fuel tank pump and the vapor canisters etc. my mechanic friend installed a preowned fuel tank and canisters etc and the code persisted, so he had the company exchange it for another one thinking it might have been faulty, and the code still persists. The HV codes are P3000 I believe but they only come up very occasionally and then go away and stay away when cleared for long periods of time. however at least 1x per week the P0171 code for the catalyst system pops up, and the P0453 never goes away. Even when I clear it it comes back immediately.

Where is the EFI M relay located?

after the fuel tank and canister replaced I now get about 38-41 mpg combined but still not what it should be.

and the engine still revs up
Rpms randomly but doesn’t accelerate itself. Just revs up randomly while in drive stopped such as at a red light . thanks for any help

 

The mechanic Prius guy believes that there might be a hybrid cell leaking to a ground? He rebuilt the battery in March 2019 he has a warranty on it till March 2020 but he’s very understanding and good on his word, he will help. Even after warranty date bc he knows it’s been malfunctioning and never really been fixed.
But he and I both are at our wits end with the p0453 code he says he’s run out of possible solutions. if there’s other smaller solutions possible I’m willing to try them surely there’s got to be a simple option or attempts since I’ve essentially paid to rebuild the whole darn car.
thanks again .

 

oscillating pattern to what ? The engine revving ? No. It’s consistent for a while and eventually goes away generally when I start driving. It doesn’t rev when in park only when sitting still while in drive.

not too worried about that part I’d rather figure out why I can’t get more than 39-40mpg.... I do a lot of hwy driving speeds 65-75 occasionally 80... but I should still see like 45mpg hwy right ?