98 Ford Taurus

My parents have a 98 Ford Taurus with a 6 cylinder engine OHC. Any rate we changed all 4 heated O2 sensor and then re-set the codes. Now the light keeps coming on and at first it said Bank 1 Sensor 1 so we replaced that one again. Then it says Bank 2 sensor 1 and we replaced that one again. Now the light is saying them both within a month. Any iseas what would cause this? I am told there is a sensor that will by pass the O2 sensors and show them as faulty but we are pulling our hair out (What is left anyway) :banghead:

What are the exact codes you are getting? They should be in the form of P0123 where "0123" could be some combination of numbers.

The codes you are getting may be indicating a problem with the DPFE sensor or MAF sensor, or any other sensor/vacuum leak that is common to both banks. A code for a lean bank does not imply the O2 sensors are faulty.

If you have a code P0171 and/or P0174, these have been addressed numerous times on the forum and you'll find some good troubleshooting info on them if you use the "Search this forum" tool from the Taurus forum main page.

Actually, I'd suggest you search the Taurus forum for any codes you get on their Taurus as many of them have been addressed at some point.

-Rod

I know about the codes and am using a Actron OBDII reader. The codes are P0133 and P0155. I work at Advance Auto Parts and know the codes are for the Heated O2 sensors for Bank 1 and 2 sensor 1. But as I said, we changed them both and checked for frayed wires. We can't detect a leak in the exhaust anywhere.
I found the mention of these codes only 3 other times with no real solution other than checking to see if there was 12Volts going to the sensors. I will have to check that this week end. Bank 1 sensor 1 is extremely hard to get to in order to check, but I will get it done. Any other thoughts other than the frayed wireing, exhaust leak or faulty sensors? I don't think the sensors are bad since they have been replaced now twice for both forward sensors? I did see one mention of a different sensor, but do not know of this one. I am not familiar with the DFPE switch.

Okay, having the exact codes helps. According to these codes, the problem would not necessarily indicate that a sensor is bad.

For the P0133 (B1S1), possible causes are:
-- Contaminated HO2S.
-- Exhaust leaks.
-- Shorted/open wires.
-- Improper fueling.
-- MAF sensor.
-- Deteriorating HO2S.
-- Air leaks.

Code P0155 indicates a problem with the O2 sensor heater circuit for sensor B2S1 (code P0155). Possible causes of this code are:
-- Shorts to VPWR in harness or HO2S.
-- Water in connectors.
-- Cut or pulled wires.
-- Disconnected wiring.
-- Open VPWR circuit.
-- Open GND circuit.
-- Low battery voltage.
-- Corrosion or poor mating terminals.
-- Damaged HO2S heater.
-- Damaged PCM.

-Rod

The PCM I have heard but the rest I had not. thanks, this gives me alot to check.

MAF = Mass Air Flow sensor. This is located between the air filter and the throttle body and will probably have between 3 and 5 wires plugged into it. If this is loose, or any of the air intake hoses are loose, you may experience driveability issues and/or various codes.

VPWR = Battery voltage, typically to the PCM or sensors.
HO2S = Heated Oxygen (O2) Sensor
GND = Ground

-Rod

Thanks Rod, what I meant though is that I had not heard that the MAF would effect the O2 sensor to give a faulty reading or that it was under that code. I sell enough of them that I defenitely know where and what it does. I had never seen that under a P0133 code before. All the Haynes book says is Heated O2 sensor B1S1 and doesn"t give any of the other items you mentioned.

Sure. The "possible causes" listed above are pasted from the Ford factory service manual for a 1998 Taurus, so they tend to have a more comprehensive list than what the more common Haynes and Chilton manuals have.

Good luck, and please keep us informed of your findings.

-Rod