Replacing O2 sensor
Thread Starter
|
New User
Joined: Jul 2004
Posts: 8
Likes: 0
Replacing O2 sensor
2001 F-150 with a 5.4L and I need to change the O2 sensor, however I am not sure if I need to change the front or rear O2 sensor. The computer scan just stated to replace O2 sensor 1/2. I did not perform the scan myself a friend did. The truck has 77,000 miles and neither O2 sensor has ever been replaced, does one O2 sensor tend to need replacing first, front vs. rear???
Thanks,
A friend of ford builder
Thanks,
A friend of ford builder
Logistics Pro
Joined: Jul 2002
Posts: 4,821
Likes: 19
From: South Dakota
I reccomend replacing them as cleaning never really works as the sensor is in side the metal tip.
Check out this link.
If you look at Rockledge's link, you'll see that 100K is the expected life span of a 4 wire O2 sensor.
I replaced all four sensors on my truck. The front ones are very tricky to get the electrical connectors undone. On the Drivers side it helps to remove the 4x4 drive shaft and on the passenger side it helps to take the tire off.
When installing mine, I had to cut my 22mm wrench in half and then I used a bottle jack handle with the open end of the wrench I cut up as my tool. When you look at the passenger front sensor, you'll see why I cut my wrench up.
Before busting them loose, I let them soak in PB Blaster overnight. A small grunt and they all popped loose.
If you decide to replace the sensors, I reccomend Bosch, but I will warn you that the Bosch book at Checkers was wrong on my rig (see the link). It may be wise to remove the sensor(s) and then head to the parts shop, for the exact same thing. If you replace all 4, you should walk out with 2 different part numbers. The fronts are a different # than the rears.
Check out this link.
If you look at Rockledge's link, you'll see that 100K is the expected life span of a 4 wire O2 sensor.
I replaced all four sensors on my truck. The front ones are very tricky to get the electrical connectors undone. On the Drivers side it helps to remove the 4x4 drive shaft and on the passenger side it helps to take the tire off.
When installing mine, I had to cut my 22mm wrench in half and then I used a bottle jack handle with the open end of the wrench I cut up as my tool. When you look at the passenger front sensor, you'll see why I cut my wrench up.
Before busting them loose, I let them soak in PB Blaster overnight. A small grunt and they all popped loose.
If you decide to replace the sensors, I reccomend Bosch, but I will warn you that the Bosch book at Checkers was wrong on my rig (see the link). It may be wise to remove the sensor(s) and then head to the parts shop, for the exact same thing. If you replace all 4, you should walk out with 2 different part numbers. The fronts are a different # than the rears.
Last edited by superrangerman2002; Feb 18, 2005 at 06:31 PM.
Freshman User
Joined: Feb 2005
Posts: 37
Likes: 1
The "rear" sensors are cat monitor sensors, not O2 sensors. Though they are basicly the same sensor, their function is completely different. Cat monitor looks for a more steady voltage reading (very little voltage fluctuation after the cats have warmed up); while an O2 sensor will rapidly fluctuate from about .1v (lean) to .9 (rich). If the O2s flucuate rapidly and the cat sensors are more stabil the PCM knows that the catalytic convertors are working properly. A bad convertor will cause the cat sensors to fluctuate like the O2 sensor.
Last edited by 1toptech; Feb 18, 2005 at 09:28 PM.
Junior User
Joined: Jul 2004
Posts: 59
Likes: 0
I don't believe anyone answered your original question of which sensor to replace. I'm not an expert, but I believe O2 sensor 1/2 means Oxygen Sensor in the 1st bank (number 1 cylinder side), 2nd sensor down line (there are two).
Elder User
Joined: Jun 2005
Posts: 740
Likes: 0
Replace the upstream o2 sensores ( the ones above the cat) those are the ones that tell the cpu how much fuel or o2 is in the system. As 1toptech said the down stream sensors raely go and only monitor the CAT. the cost is about 59.00 a piece.
Lance
Lance
Thread
Thread Starter
Forum
Replies
Last Post
NinthGenF-SeriesOBS
2004 - 2008 F150
2
May 3, 2016 08:15 AM
breeaad
Explorer, Sport Trac, Mountaineer & Aviator
3
Jul 10, 2012 09:02 AM
