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WRX/Focus:)
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Discussion Starter #1
I own a 2000 ford focus wagon with the 2.0l Zetec DOHC in it, and I took it down to Advance auto parts to use there OBDII reader, and it says I need to replace the front o2 sensor and both right and left rear speed sensors.

1. How does the o2 sensor come out? Do I need a special tool, or is there a trick?

2. Where are the rear left and right speed sensors? Are they talking about on the automatic trans, or the rear drums? Cause I don't see any sensors on the rear drum brakes?

Thank you for helping.

Djzx3
 

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1.) o2 sensor socket
2.) the sensor ring is on the back of the wheel bearing and the sensor goes in the back between the 4 bolts holding the spindle.

for the sensors check the connections first (when i pulled mine they were full of crud i had to clean out.)
 

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Waaaaaaait a minute. Before you go purchasing the sensor, exactly what were the codes that were pulled? Sometimes you get codes for the O2 sensor that are not really an O2 sensor failure. For example, if the heater circuit in the sensor is not working, it might simply be a fuse.

Now if the car has over 100k miles, then you're not really going wrong with replacing an O2 sensor. However, I don't see the sense in spending $200 not to fix the problem, and having to go back and spend another $5 to get 2 fuses if that is the case.

We need the code numbers like P0172 to check against our DTC code list.

The same thing goes for the wheel speed sensors. You should jack up the vehicle securely and safely, then trace down the wiring for the sensors before you purchase new sensors. Road debris could've damaged the wiring harness, or it could be unplugged inside the vehicle. I only suggest that because 2 sensors are bad at the same time.
 

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WRX/Focus:)
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Discussion Starter #4
The guys came out with me a told me what the scanner said the problem was, I don't know the codes, but if I can spend $5 bucks first, then it's more worth the try.

Where are the two fuse's for the o2 sensor? And I want to add that someone put bosch crap in there for a front o2 sensor, so it wouldn't surprise me if it comes down to that.

As far as the speed sensor, I will defiantly track the wiring first. But it's good to know atleast where they are located.
 

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WRX/Focus:)
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4,940 Posts
Discussion Starter #5 (Edited)
Okay I got the codes:

The rear right sensor code is B1235.

The left rear sensor code is B1236

And the o2 sensor is coming up P0135, and the guy said it was bank 1 sender 1?

Does this info help you to help me?

EDIT: and would the o2 sensor make the car not perform well at higher speeds? I was coming up a slight incline and took the O/D off and tried to race up the hill a little, I got to 60MPH, and it seemed like the car didn't want to go faster?

Could this^ be just because I took it out of O/D, and O/D's dop out point is 60MPH?
 

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WRX/Focus:)
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4,940 Posts
Discussion Starter #6
This is from our fault code thread?

B1235 Window Feedback Failure
B1236 Window Feedback Loss of Signal

And

P0135 - HO2S Sensor Circuit Malfunction (HO2S-11) During testing the HO2S Heaters are checked for opens/shorts and excessive current draw. The test fails when current draw exceeds a calibrated limit and/or an open or short is detected. Short to VPWR in harness or HO2S.
Water in harness connector.
Open VPWR circuit.
Open GND circuit.
Low battery voltage.
Corrosion or poor mating terminals and wiring
Damaged HO2S heater.
Damaged PCM.
Wiring.
Damaged HO2S heater.
Damaged PCM.

Is this correct, and what does all this^ mean? Does this mean P0135 could be any one of those?
 

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Is this correct, and what does all this^ mean? Does this mean P0135 could be any one of those?
Yes, so I'd check to see if the wiring is damaged before purchasing a new sensor. You do get wiring from the sensor to it's connector when you get a new OEM sensor. Do not purchase the generic sensor, always get the OEM type, and we have had more than a few have issues with the Bosch sensors.

Is your ABS light on? If a wheel sensor was bad, the ABS light would be on.
 

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WRX/Focus:)
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Discussion Starter #8 (Edited)
Yea my ABS light is on, my brake light is on, and my check engine light is on.

And I checked the fluid level, so I know the brake light ain't on because of low fluid, so could that be connected to the same thing? The brake light doesn't show on start up, only after driving half a mile does it come on.

But then what does the P code mean? I thought it was just the o2 sensor or maybe the wiring or two fuse's? What's all this other stuff it is talking about?

P0135 - HO2S Sensor Circuit Malfunction (HO2S-11) During testing the HO2S Heaters are checked for opens/shorts and excessive current draw. The test fails when current draw exceeds a calibrated limit and/or an open or short is detected. Short to VPWR in harness or HO2S.
Water in harness connector.
Open VPWR circuit.
Open GND circuit.
Low battery voltage.
Corrosion or poor mating terminals and wiring
Damaged HO2S heater.
Damaged PCM.
Wiring.
Damaged HO2S heater.
Damaged PCM.
 
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