[img]Good evening 4AG Family.
I finally got some time to go back to my FX and the 4AGE 20V Silvertop Engine.
I keep getting the light under the dash to come on after driving at high speed, now it will stay on immediately after I crank the car.

I jumped the TE1 and E1 at the diagnostic plug and the codes I read was as follow:
12 (RPM Signal)
21 (Oxygen Sensor Signal)
41 (Throttle Position Sensor)
42 (Vehicle Speed Sensor Signal)

I kept thinking the vehicle was running to lean as I keep smelling fuel in the cabin (it turned out to be a leaking fuel hose fitting he engine).
but I messed with the MAF (Mass Air Flow Meter), now I don't know if I have it set correctly or if I just screwed up the Air to Fuel Ratio (didn't take a picture before I moved it, and cannot remember the position it was at first) if anyone have any idea how to tune the MAF properly, I will be greatly appreciated.

Regarding the ECU codes above.
any help as how to fix those codes?

I also messed with he throttle body position sensor. I moved it because the car was too high on RPMs (above 1300) and hoping to bring it down, I messed with the throttle body and MAF at the same time.

So, any help to bring does to the right tune to how to fix those codes, I will appreciate greatly.
Thank you all in advance for the support.

Update,
If I replace all those sensors, should that take care of all codes, or should I take it to a dealer for troubleshooting?

Thanks.

When you have that much codes from that much different and unrelated parts, my first thought is that you've got a messed up ground or something like that for the ECU.

RPM signal comes from the dizzy
O2 sensor is in the exhaust
TPS is on the throttle body
Speed sensor goes through the instrument cluster that generates a signal from the gearbox

Small chance these go bad all at the same time.

I'd start with checking electrical connections and especially grounds if I were you.

Also toyota ecus of this era fail often (info online). Leaky capacitors. Hope it's not

Jinx is right, it wouldn't hurt to open up the ECU and look for bad capacitors. If they are swelled or leaking it can cause all sorts of issues. It's an easy cheap fix. If I remember there are 7 of them to replace. Here is a pic of them. Mine were bad. I think I paid two bucks for each one.
https://photos.app.goo.gl/XYPGAAKbtreedRXi6