Hi all hope your doing well... I recently acquired a 2000 explorer and im having a problem with 02.

[Tleavitt7]

The first code ia 1131 i think lack of o2 sencer causing lean con. Another code is p0135 heater in the o2 sencer one other code i forget now but it pointed to a o2 sencer witch way do i go from here . please any advice is gratefully appreciated thanking you in advance

 

[MrQ]

Basically the codes are telling you that both upstream sensors (the sensors closest to the exhaust manifold) are bad. You need to replace them.

Have the MPG's dropped, is the engine running rough, and/or do you have a loss of power? Those are good indicators that the codes are pointing you in the right direction.

 

[Turdle]

Ok, you have 4 o2 sensors on your truck. 2 primary ( upstream) for engine control, and 2 secondary ( downstream) for catalytic converter monitor. The engine is set up in 2 banks of 4 cylinders each. Bank one cylinders 1-4 on passenger side, bank 2 cylinders 5-8 on driver side.


Both codes point to bank 1 sensor 1 being dead, and it is the one which will be the furthest upstream sensor on the passenger side , you might be able to see it through the wheel well opening once you remove the inner liner. It will be right in the pipe behind the primary cat ( yeah, 4 of those too)

The connector is a PITA to get to from underneath, but simple to reach if you remove the center console . Read the below "how to" and you'll see a picture of where the connectors are located.

2nd gen console removal

edit. You might try this, since all o2 sensor signals run thru these connectors, it might be worth a shot to reseat them

2nd gen issues? Try this first!

 

[Tleavitt7]

I have replaced them and the codes come up the same yes the mpg has dropped and no I'm not running rough for anythingl

 

[MrQ]

Both codes point to bank 1 sensor 1 being dead, and it is the one which will be the furthest upstream sensor on the passenger side

P0135 O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)
P1131 Lack of Upstream Heated Oxygen Sensor Switch - Sensor Indicates Lean - Bank No. 1

You need to get the codes cleared and completed a drive cycle, (about 100 miles) so the computer can relearn. If the codes come back up during the drive cycle then we are looking at another issue.

 

[410Fortune]

Tell us about your 2000 is it a v6 or v8?
How many miles?

 

[Turdle]

P0135 O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)
P1131 Lack of Upstream Heated Oxygen Sensor Switch - Sensor Indicates Lean - Bank No. 1
.

P0135

o2 sensor heater malfunction bank 1 sensor 1

OBD-II Diagnostic Trouble Codes (DTCs)

@Tleavitt7 check fuse #13 in the fuse box under the hood. It protects the o2 sensors.

did you try reseating the connectors yet?

Also, check the vehicle side of o2 sensor connector for loose pins inside. Sometimes they get shoved back into the connector housing which prevents them from actually making contact. Also, you might check the wiring for frays.

Are you sure you replaced the upstream sensors? Picture of sensor you replaced please.

 

[MrQ]

P0135

o2 sensor heater malfunction bank 1 sensor 1

OBD-II Diagnostic Trouble Codes (DTCs)

My reference said otherwise.

I any case, Jon has some good info to try. Hopefully our advice will help you solve your problem!