Code 172
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From: MICHIGAN
Code 172
This is my second post for a 1996 F250, 351 CID, original owner (me!).
I read the OBD1 code,172, Heated Exhaust Gas O2 Sensor (HEGO) Lean Bank 1.
There is only one O2 sensor I can locate on the exhaust pipes (definetly not two like some cars).
My questions (before I spend $) are:
1. Is the O2 sensor what the code refers to or are there hidden sensors on the banks (the code book shows other codes for Bank 2)?
2. If it's a showing lean code could it be a different problem upstream from
the sensor?
Thanks.
I read the OBD1 code,172, Heated Exhaust Gas O2 Sensor (HEGO) Lean Bank 1.
There is only one O2 sensor I can locate on the exhaust pipes (definetly not two like some cars).
My questions (before I spend $) are:
1. Is the O2 sensor what the code refers to or are there hidden sensors on the banks (the code book shows other codes for Bank 2)?
2. If it's a showing lean code could it be a different problem upstream from
the sensor?
Thanks.
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Joined: Sep 2004
Posts: 941
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The codes are generic for many vehicles. When it says "bank 1", in your case it is referring to the only oxygen sensor -- the one you already found.
If the heating element does not work, or the HEGO sensor has failed open, it will read lean. If the sensor is merely dirty, it will read rich.
If the code comes back quickly, and there are no obvious symptoms of lean operation, and the sensor has a lot of miles on it, go ahead and change it out. It doesn't cost all that much. If it takes a week of driving for the code to come back, it may be just a fluke, or low fuel pressure, vacuum leak, or any number of things, and swapping the sensor is just whipping out the parts change shotgun.
Warm the engine up and run a KOER test. The computer will set a code if it cannot get into closed-loop mode due to a dead sensor.
If the heating element does not work, or the HEGO sensor has failed open, it will read lean. If the sensor is merely dirty, it will read rich.
If the code comes back quickly, and there are no obvious symptoms of lean operation, and the sensor has a lot of miles on it, go ahead and change it out. It doesn't cost all that much. If it takes a week of driving for the code to come back, it may be just a fluke, or low fuel pressure, vacuum leak, or any number of things, and swapping the sensor is just whipping out the parts change shotgun.
Warm the engine up and run a KOER test. The computer will set a code if it cannot get into closed-loop mode due to a dead sensor.
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From: MICHIGAN
For FeFarms
I did the KOER test and got the same 172 code. It appears the O2 sensor may be toast. I guess...I did notice when I took it for a spin this evening, engine not quite warmed up, there was a slight stumble or two when accelerating after slowing down for a turn. Cleared up once the engine was warmed though. Do you think a bad O2 sensor would cause this since I also am showing the 172 code?
Last time I'll ask. I'll get the sensor Monday. BTW, I checked all vac lines and they are all good. My baby has never acted up, guess it's getting old like me.
Thanks again, John (In cold Michigan)
Last time I'll ask. I'll get the sensor Monday. BTW, I checked all vac lines and they are all good. My baby has never acted up, guess it's getting old like me.
Thanks again, John (In cold Michigan)
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Joined: Sep 2004
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Hesitation when cold suggests there isn't enough enrichment for low temps. There really could be a lean condition. Or the ECT may be bad and the computer may not be applying sufficient cold temp enrichment. Or the dead or dying oxygen sensor may have caused the computer to learn some "bad habits" in the long term fuel trim, which carries over into cold weather ops.
The oxygen sensors have an expected llifetime of around 60000 miles. If yours has more than that, you shouldn't feel bad about replacing it, even if it turns out to not be the problem.
The oxygen sensors have an expected llifetime of around 60000 miles. If yours has more than that, you shouldn't feel bad about replacing it, even if it turns out to not be the problem.
Elder User
Joined: Sep 2004
Posts: 941
Likes: 4
Hesitation when cold suggests there isn't enough enrichment for low temps. There really could be a lean condition. Or the ECT may be bad and the computer may not be applying sufficient cold temp enrichment. Or the dead or dying oxygen sensor may have caused the computer to learn some "bad habits" in the long term fuel trim, which carries over into cold weather ops.
The oxygen sensors have an expected llifetime of around 60000 miles. If yours has more than that, you shouldn't feel bad about replacing it, even if it turns out to not be the problem.
The oxygen sensors have an expected llifetime of around 60000 miles. If yours has more than that, you shouldn't feel bad about replacing it, even if it turns out to not be the problem.
