The sensor on the front of master cylinder started to melt. some kind of short melted the plug to What do i do?

OXY SENSOR IS SHORTED(was)AF (named by Lexus oddly)
THE FUSE BLOWS IF SHORTED DID IT? 25amps blew up?
AND WHICH RELAY, EXACTLY.
both p1135/55 means , B1S1 and B2S1 both front sensor heaters are dead but gee wiz with relay pulled sure they are. dead.
AF heater relay runs both those 2 front O2 sensors
and if either of the 2 short. fuse marked AF heater fuse blows 25AMPS
The heaters are spec at 5 ohms so each heater uses 3amps 6 total paired, and 25amp fuse does not blow.
but if the 2 heaters B1S1 and B2S1, short the fuse blows.
so bad 02 front sensor. or wires to them melted or cut in half
wires on O2 , with clamps missing allow wires to touch 2000f header pipes(exhaust ) and melt and burn up, and then short.
or even burn open.

or put in the wrong 2 front 02 sensors or used the cheap ones
$20 that are hand wired, and wired up wrong.. (done lots but not wrong yet, I'm careful) I run BOSCH only, and or OEM fit
and easy to pop in, the Bosch web site has the Ecatalog to get the correct ones. from them.

These two codes indicate failures of the primary ignition circuit on cylinders 2 and 4. These two cylinders are the two leftmost cylinders on the front bank. These failures are primary ignition failure codes, meaning the failure is between the battery and the coil, not the coils themselves. Could be an open or short in the wiring. Use a 12-volt non-powered test lamp to verify START/RUN voltage at the ignition coil harness connector. Check the coil driver circuit for open, short to voltage, or short to ground.

You must have a short in the engine harness.

the book , called the FSM answers that. and that code. 138
you never said which engine, (or if its a california car? they can be diffr)
but 138 is clear.
its bad, or its wires are all melted and shorting together.
the sensor is 1/2 (jeep parlance) for B1-S2, bank1 sensor 2.
bank one depends on the engine.
bank one means that exhaust band that resides near cylinder 1.
sensor 2 means, that sensor to the rear of the CAT.
1: check the wires there. melted? from sensor upward , no burns.
2: bad sensor.
its the same answer for all cars. all engine, gas. 1996 to now.
USA.
the rear sensor only watches the CAT, to see if its works.
the rear sensor does not control engine fuel rates.
see emmision chapter
see exh. chapter

http://www.jeep4x4center.com/knowledge-base/index.htm?utm_source=cj#service

under exhaust
see page 4. see there are 2 engines, and FED and Calif.
setups.
this page 4 is clear, no? see them there.?
the inline 6 in calif runs a very odd, split exhaust manifold.
and has not 2 sensors but 4. (odd duck that)

if a 4.7L see page 6. (pdf pages)
under exhaust.
that cover this, ask questions.

Check the crank position sensor. Had alot of irratic misfire and starting issues related to that little guy.

Short of jacking up the wheel and putting a new car underneath, you've just about covered all the possibilities. But I wonder, perhaps in your attempts to solve this, if you have inadvertantly introduced another fault? As you know, the brake master cylinder on a disc braked vehicle has no static valve. If there were to be a static valve in the master cylinder, the brakes would lock on after a few pumps. But this would affect both front wheels. There could also be a collapsed section in one of the flexible hoses which would let fluid through for bleeding but not allow the fluid to return. this would hold the brake on too. When you had the cliper off, did the rotor trun freely?

check the abs sencer on the front wheels, some time they get hot and melt, that make them short out.

the air pump will not change fuel mixture it is used to reduce emissions by adding air to the exhaust to allow the fuel to finish burning
after you replaced all those sensors did you reset the computer (unhook the battery for about 5 min)?

i would pull the plugs clean them, with the plugs out crank it over to clear the cylinders. reinstall the plugs and start it

you problably cooked your engine,sp.plugs melted! cylinders must be scored,head and,or engineblock cracked!you can check compression in cylinders,but not looking good for motor!

I had a similar problem with my anti-lock brake.
One of the will wear down. I took it to the dealer, could not tell why.
Until one day the a brake light came on. It was a bad sensor. Replace the bad sensor and the problem went away.
The mechanic plug a portable instrument and drive the car around until he find out. (The brake light came on, then off.)
This anti-lock brake system is control by sensors and it one is not functioning properly then you have a problem.
I do hope this help you.