I have two codes that will not go away po36 and po37. These codes dill with the 02 sensor . I installed a new 02 cleared codes drove it. The light returned. Thanks

These may be few possible reasons why the check engine light won't go away after replacing the O2 sensor in your 2000 Mitsubishi Eclipse V6

·The wrong O2 sensor was replaced or the O2 sensor is properly connected to the wiring harness(any signs of damage or corrosion).
·Sometimes, issues with the engine, such as misfires, vacuum leaks, or problems with the fuel system, can trigger the O2 sensor to report a problem. Ensure your engine is running smoothly and there are no other issues that could affect air/fuel ratios.
·The new O2 sensor is defective. If the O2 sensor is working properly, then the check engine light could be due to another problem with the exhaust system, such as a leak or a problem with the catalytic converter.
·Problem with the wiring to the O2 sensor. If the wiring to the O2 sensor is damaged or corroded, it can cause the sensor to malfunction and trigger the check engine light. To diagnose the exact cause of the problem, you will need to have the car scanned by a qualified mechanic. The mechanic will be able to read the trouble codes from the computer and use that information to pinpoint the problem.

Real simple

None of the shops you went to,
know how to diagnose a vehicle

I think your statement about one monitor,
is the evap system ,because they can test
the gas cap,the others have to run clear,
at least in New Jersey

Almost seems like the people that come to this site

Your shop just throw parts at the codes & no testing
to find a problem

If the problems are solved, you don't have to clear the codes

Clearing the MIL Lamp or check engine light, clears all data,
emission monitors,& freeze frame data set at the time fault
codes are set,so you got nothing to work with to find a problem

So never clear fault codes after a repair,let the monitors do their thing

All sensors are aftermarket sensors-so that is nonsense

That should have been a clue to forget that shop

The same companies make sensors for everyone,
new vehicle or used

Vehicle manufactures stamp sheet steel & make bodies
& assemble purchased components only

This also happened to me and it was the heater matrix, whatever that is

did you check your o2 sensor fuses?

What your asking, is how to make a malfunction light
go away from your dash, so you can forget you have a
problem & make no attempt to repair the car

Until you find & resolve active OBD2 Codes that actually set
a MIL or Check Lamp it will keep coming back

Every time you clear a code you have to run a drive cylce in
some cases to start the procees over, as you need those codes
to diagnose the issues

The codes that are there, do not tell you what to replace

Without writing a book here, just study OBD Systems online &
take the car to a repair shop

It is beyond your ability at this time to figure out

P0135 is 02 heater circuit ( Bank 1, sensor 1 ). P0138 is 02 circuit high voltage ( Bank 1, sensor 2). It is a good idea to replace all 4, 02 sensors at the same time, otherwise the 2 new 02 sensors on bank #1 will be transmitting Data back to the computer at a faster rate then the old ones on bank #2 And this could cause other problems. Remember to have the codes cleared from the computer after all repairs are finished. If you do not the computer will keep turning on the check engine light.
-also that way if the light ever comes on again you already know it will be for something new.Good Luck and have a good XMASS.

MOST OF THE TIME AN 02 CODE DOES NOT MEAN REPLACE 02 SENSOR..SOME AUTO PARTS STORES WILL SCAN YOUR CAR..TELL YOU CODE 02 SO PEOPLE AUTOMATICALLY REPLACE SENSORS...IF YOU CLEAR THE CODES DOES THE CHECK ENGINE LIGHT COME BACK ON RIGHT AWAY OR DOES IT TAKE A LITTLE TIME... IF IT TAKES A LITTLE TIME THEN YOU HAVE SOME PROBLEMS THAT ARE CAUSING THE EMMISSIONS TO BE OUT OF RANGE.. IF THE LIGHT COMES BACK ON RIGHT AWAY YOU HAVE A PROBLEM IN WIRING HARNESS BETWEEN THE SENSOR AND ECM....MAIN COMPUTER.....OR SECONDLY POSSIBLE PROB IN THE MAIN COMPUTER...GET SOME OF THOSE ANSWERS AND FIND THE EXACT CODE THAT RETURNS THEN GET BACK WITH ME FOR MORE HELP

I would take it back and see what the new code is. You may have encountered a completely different issue that may need to be addressed.

I had to replace both o2 sensors on my 2002 Tundra after about 50K. Toyota recalled this problem afterwards and refunded my money. My solution to you is to not worry about which one is bad and go ahead and replace both, because I had one bad and before I could replace it the other went bad also. PS: You'll have to purchase a special socket to remove them and unless you pruchase the Toyota product ( I used O'Reilly parts), you have to cut and splice the wires with a waterproof splicing kit included with the sensors. Just follow the instructions, not a hard job.

There are fuses for oxygen sensor heaters. Check for 12 volts to the sensor with key on.