wire O2 sensors

[humaxxx]

hello,

We have a problem with our mustang 5.0. If we dump the codes from the computer we get 41 and 91. We have bolt on new o2 sensors but we still get the codes 41 and 91. We have also measure the resistance between the ground from the computer and the sensor. And the resistance between the + from the sensors and the pins/wire at the computer (29/43). This was all OK.

But at the sensors there is a third wire......wat is the use of this third wire...must there be a 12v signal at this wire????????:

Can somebody help us

thx

 

[jrichker]

hello,

We have a problem with our mustang 5.0. If we dump the codes from the computer we get 41 and 91. We have bolt on new o2 sensors but we still get the codes 41 and 91. We have also measure the resistance between the ground from the computer and the sensor. And the resistance between the + from the sensors and the pins/wire at the computer (29/43). This was all OK.

But at the sensors there is a third wire......wat is the use of this third wire...must there be a 12v signal at this wire????????:

Can somebody help us

thx

The third wire is usually the 12 volts for the O2 sensor heaters.


Diagram courtesy of Tmoss & Stang&2birds

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine/

Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

Fuel pump, alternator, ignition & A/C wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

Computer, actuator & sensor wiring
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Fuse panel layout
http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif

Vacuum routing
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

 

[HISSIN50]

Those codes do not indicate O2's being the issue - they indicate a lean condition. This can be due to a vacuum leak, bad MAF or any number of other factors.

Just something to consider as you troubleshoot.

Good luck.

 

[humaxxx]

I have measure the voltage on the third wire and there is no 12v signal on the wire.......Can that be the problem???? Or as the engine is warm the heater inside the o2 sensor is no more nessarly???

thx

 

[humaxxx]

nobody!!!!

The car is running very rich ...its stinks badly!!!

 

[jrichker]

Go back to the diagram I posted. and look at the lower LH vcorner. You will find the O2 sensor circuit. If there is no 12 volts on the gray/yellow wire, then the fuseable link, or wiring is faulty.