Code 172 (oxygen sensor) after replacement
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Code 172 (oxygen sensor) after replacement
Good morning,
Since the O2 sensor is one of the components that determines the amount of fuel delivered, my best guest on where to post this question was in the fuel section. Let me know if there is a better place to post this.
I read the code from my 93 F150,4X4, 351 and it was 172 (lean). The truck has 112K miles and the O2 sensor has never been changed so I replaced it. After a few weeks the code came back.
I was going to check the fuel pressure over the weekend but only have the GM connector on my fuel gauge. Since it is relatively easy, I replaced the fuel filter since it had been awhile and I still have the 172 code. I had my fuel pump replaced about 2 years ago. Has anyone had this problem? Is the next step to test the fuel pressure.
The truck runs fine and gets about 15 miles/gal. The code only comes on after about 8 miles of driving and stays on until the truck is shut down. I never seem to get lucky just replacing parts and I'm up to my ears in wrenching on my Vette. Can anyone let me know what worked for them?
Thanks, Beth
Since the O2 sensor is one of the components that determines the amount of fuel delivered, my best guest on where to post this question was in the fuel section. Let me know if there is a better place to post this.
I read the code from my 93 F150,4X4, 351 and it was 172 (lean). The truck has 112K miles and the O2 sensor has never been changed so I replaced it. After a few weeks the code came back.
I was going to check the fuel pressure over the weekend but only have the GM connector on my fuel gauge. Since it is relatively easy, I replaced the fuel filter since it had been awhile and I still have the 172 code. I had my fuel pump replaced about 2 years ago. Has anyone had this problem? Is the next step to test the fuel pressure.
The truck runs fine and gets about 15 miles/gal. The code only comes on after about 8 miles of driving and stays on until the truck is shut down. I never seem to get lucky just replacing parts and I'm up to my ears in wrenching on my Vette. Can anyone let me know what worked for them?
Thanks, Beth
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From: Louisville,Ky.
It doesn't mean the the O2 sensor is bad, it is just detecting a lean condition that it can not correct. I would look for a vacuum leak somewhere like a dry rotted hose or something.
I do not know if your truck has a Mass Air Flow sensor on it or not. If so, I would spray the little wires in it with carb cleaner and see if this helps. Also, if it has mass-air, make sure that there is no air leakes between the throttlebody and the mass-air meter or it will not get the correct airflow across it and will also make it run lean.
Jimmy
I do not know if your truck has a Mass Air Flow sensor on it or not. If so, I would spray the little wires in it with carb cleaner and see if this helps. Also, if it has mass-air, make sure that there is no air leakes between the throttlebody and the mass-air meter or it will not get the correct airflow across it and will also make it run lean.
Jimmy
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Thank you for the quick reply, Jimmy. If I have a MAF sensor, where would it be located and what does it look like? The truck is old enough now that I have to get the Ford service manual but I don't have one right now.
The vacuum leak check is a good idea too, since I live here in the desert where pack rats like to hang out in open garages and chew wires in engine compartments. They've done some pretty extensive damage in the past. I forgot about those little guys, looks like I'll have to break out the "have a heart" trap again.
Beth
The vacuum leak check is a good idea too, since I live here in the desert where pack rats like to hang out in open garages and chew wires in engine compartments. They've done some pretty extensive damage in the past. I forgot about those little guys, looks like I'll have to break out the "have a heart" trap again.
Beth
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Beth, I'd just shoot the little critters and rip their heads off.
Just kidding.....
The 172 code indicates a lean condition on bank 1. This is the passenger side. First try tightening the intake manifold bolts on this side.
If this dosen't turn the CEL off, then get a propane bottle and spray (unlit) around the passenger side of the intake, and see if the idle increases. If it does, you've found the leak.
Just kidding.....The 172 code indicates a lean condition on bank 1. This is the passenger side. First try tightening the intake manifold bolts on this side.
If this dosen't turn the CEL off, then get a propane bottle and spray (unlit) around the passenger side of the intake, and see if the idle increases. If it does, you've found the leak.
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From: Louisville,Ky.
Hey there Loneranger, in 93, I think that they only had 1 O2 sensor and it is located in the converter H pipe. They didn't start all of the laft bank /right bank stuff until 96 when the OBD II came out.
If you have a mass-air sensor, it would be in the air inlet hose close to the air cleaner. It should have a 4 wire plug on it.
I would do the carb cleaner down the intake on both sides and on the gasket between the upper and lower 1/2's of the intake. Also around the threottlebody.
Jimmy
If you have a mass-air sensor, it would be in the air inlet hose close to the air cleaner. It should have a 4 wire plug on it.
I would do the carb cleaner down the intake on both sides and on the gasket between the upper and lower 1/2's of the intake. Also around the threottlebody.
Jimmy
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Jimmy, thanks for correcting me. I was reading the 172 code description out of the book, and didn't pay attention to the model year.
Beth, the fact that you can drive it for 8 miles before the CEL lights, means that it's in warm-up/open loop at that time. When it switches to closed loop, that's when the O2 sensor reads a lean condition. Jimmy's suggestion to clean the MAF is a good one. I'm pretty sure you will have a MAF on a 93.
.........just as an afterthought.....an old note dropped out of my code book that had codes 172, 173, and 186 written on it. They were from a 92 Mustang I previously owned. A new O2 sensor cured these codes, so I suppose the O2 sensor could still be bad on yours, Beth......
Beth, the fact that you can drive it for 8 miles before the CEL lights, means that it's in warm-up/open loop at that time. When it switches to closed loop, that's when the O2 sensor reads a lean condition. Jimmy's suggestion to clean the MAF is a good one. I'm pretty sure you will have a MAF on a 93.
.........just as an afterthought.....an old note dropped out of my code book that had codes 172, 173, and 186 written on it. They were from a 92 Mustang I previously owned. A new O2 sensor cured these codes, so I suppose the O2 sensor could still be bad on yours, Beth......
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From: peoria, az
Might want to look at that bank 1, bank 2 thing. I believe they used that as far back as 90-91. Also check the sensor grounds. I think that the O2's have their own ground and it has to be a good connection.
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Thanks all..the code didn't get set today on my 25 mile drive to work. I believe that it is in closed loop after 8 miles. I monitor my Vette with a laptop and monitoring software and it usually goes closed loop after about the first mile. Without the monitoring software for my Ford, it's difficult to tell.
I'll be checking vacuum lines this weekend and clean my MAF sensor. I did a search on the forum and found a picture of the sensor and the cleaning procedure. In the mean time I better setup the trap just in case that little rodent wants to get warm at night in my engine compartment. I can't kill the little guys...they look little a gerble.
I'll let you know what I find. Beth
I'll be checking vacuum lines this weekend and clean my MAF sensor. I did a search on the forum and found a picture of the sensor and the cleaning procedure. In the mean time I better setup the trap just in case that little rodent wants to get warm at night in my engine compartment. I can't kill the little guys...they look little a gerble.
I'll let you know what I find. Beth
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From: alaska
if its coming in in closed loop, did you remember to reset it ? on some vehicles they reset them selves after a number of starts , if thats obdII it may be the problem, some shops will sit in your car and turn the ign. switch the number of times it takes, good luck,bob
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