02 sensor
02 sensor
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Joined: Oct 2008
Posts: 1,145
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From: Hernando Ms
To add to the previous reply,if the 02 sensors have more than 80 thousand miles on them,they need to be replaced.You should have 4 of them..2 upstream,and 2 downstream....the upstream sensors(on the exhaust manifolds) control the computer,while the downstream ones tell the computer if the converters are doing their job.If you think its the 02 sensors,replace the upstream ones first.
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Joined: Jan 2004
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From: St Louis
Unless defective, there is ZERO reason to replace the downstream sensors. They don't "wear out" very quickly and they don't have any effect on fuel economy or engine operation. Unless they fail, they often last the life of the vehicle.
Heater circuit faults, by themselves, will not cause an engine to run poorly. Your fault is other than the O2 sensors unless one of them has its wiring harness shorting the heater circuit to an exhaust pipe, drive train component, or chassis component.
If you follow the above advice and blindly replace all four sensors, you will waste at least $250 and probably still have the problem.
Steve
Heater circuit faults, by themselves, will not cause an engine to run poorly. Your fault is other than the O2 sensors unless one of them has its wiring harness shorting the heater circuit to an exhaust pipe, drive train component, or chassis component.
If you follow the above advice and blindly replace all four sensors, you will waste at least $250 and probably still have the problem.
Steve
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Joined: Nov 2004
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From: Salt Lake City, Utah
Yeah, the heater problem by itself does not pose any problems, but a sensor that has a failed heater probably needs to be replaced anyway. Also, the O2 sensor does not work as well below certain temperatures, and on many vehicles, the sensor may drop below that temperature unless you are doing sustained vehicle speeds. So when you stop at a light, the sensor might cool off to the point that it cannot read accurately. This can affect your economy. Its hard to say whether or not this is actually happening in your vehicle. I would recommend replacing both upstream sensors if they have more than 80,000 miles on them. Leave the downstream sensors alone unless you get a specific code indicating a problem with them.
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Joined: Oct 2003
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From: SoCal
On my 97 Explorer it's mini fuse 11 under the hood in the power distribution box.
But, check the fuse list in your owners manual.
Edit Or a quick look at the "engine controls" wiring diagram will tell you.
autozone.com might have the wiring diagram.
I think most -but not all- Fords do have the "hego system" fuse.
But, check the fuse list in your owners manual.
Edit Or a quick look at the "engine controls" wiring diagram will tell you.
autozone.com might have the wiring diagram.
I think most -but not all- Fords do have the "hego system" fuse.
Hotshot
Joined: Jan 2004
Posts: 19,762
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From: St Louis
The Exploder's electrical system is completely different from your F150. You need to look in your owner's manual.
The heaters are used to bring the O2 sensors up to temp more quickly so the PCM can better control emissions at cold startups. Once the exhaust stream has heated the sensors after the first couple of minutes, the heaters aren't needed again until the next cold start. Other than that specific limited purpose, their failure will do nothing more than slightly elevate emissions.
The heaters are used to bring the O2 sensors up to temp more quickly so the PCM can better control emissions at cold startups. Once the exhaust stream has heated the sensors after the first couple of minutes, the heaters aren't needed again until the next cold start. Other than that specific limited purpose, their failure will do nothing more than slightly elevate emissions.
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Joined: Nov 2004
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From: Salt Lake City, Utah
It is still a good idea to replace older sensors, because once they start to malfunction, they will decrease your gas mileage, and can also damage the emission components such as the EGR and catalytic converter. The sensors are cheaper to replace than those parts. So basically, I am saying replacing sensors with over 80,000 miles on them is preventive maintenance. And any gain in fuel economy is always a good thing and usually results in more power too.
