Hello
I had problems with my car for 2 days already
Engine will shut off while driving
And yesterday happened again but this time i could not start again
It will start go up to 6k RPMs and then shut off
Towed the car to a mechanic (i dont have a trusted one) and plugged it on the computer and said P0121
So he said its the Throttle/Pedal Position Sensor/Switch "A" Circuit Range/Performance Probl
Now he is trying to charge me $500 to switch the pedal sensor or replace the entire throttle body for over $1000

Does this sound accurate?

Edit : Car is stock, no mods so far

 

Hmm could possibly be a vacuum leak.

If the throttle body checks out bad, I don't mind letting mine go for you for cheap. I run a RX-8 throttle body.

 

Update, he Cleaned the Throttle body, now car starts but while driving rpms drops from 4k to 2.5k (at 40 mph) then goes back up
CEL turned on again and shows P0505

I dont know what to do

 

Sounds like a vac leak. Are all the hoses that go to the throttle body and intake manifold connected and in good condition? You can also try disconnecting the neg battery terminal, wait about 15 mins, then re-connect it, start the car and let it idle until the fans come on or 20-30 mins. That will let the ECU relearn the idle conditions. If the CEL comes back, then you got another problem.

 

all the hoses look ok, tried disconecting the battery and start again for 20 mins, fans came on, re started and baam CEL on again, dont have a computer on me to read the code

 

My 2008 xB is throwing the p0121 code sometimes all my lights come on then my car is in limp mode until I shut the car off and turn it back on I need help and ideas on how to fix this and why this is happening