p0172 problem
p0172 problem
I've run into a problem I can't seem to get solved. I keep getting a p0172 warning engine running rich bank 1. I took the car back to the dealer I bought it from, not a Nissan dealer. They sent it out to a mechanic, who replaced the oxygen sensor, which didn't fix the problem, then replaced the Mass Air Flow sensor, which didn't fix the problem, then tested the fuel regulator, which was supposedly fine, then replaced an injector. I now have the same code in the computer but it hasn't lit the check engine light yet. Also since I got the vehicle back my idle has dropped nearly 100rpm from where it was at before, and my dimmer switch on the dash that used to work no longer works and the dash lights are on bright all the time. Can anyone help with the warning, or suggest how the rpms and dimmer malfunctioned.
Re: p0172 problem
Too rich?
Check the air filter
What gas are you burning? 85, 87, 90+
Injector pattern, injector timing, fuel pressure too low
Blocked air conduit of feed air
Temperature range of the plugs
Inlet valve, timing, spacing, weak spring(s)
Carboned top end especially if high octane used when regular is recommended
Inlet throttle body filthy
Are these items in clean shape?
Check the air filter
What gas are you burning? 85, 87, 90+
Injector pattern, injector timing, fuel pressure too low
Blocked air conduit of feed air
Temperature range of the plugs
Inlet valve, timing, spacing, weak spring(s)
Carboned top end especially if high octane used when regular is recommended
Inlet throttle body filthy
Are these items in clean shape?
Re: p0172 problem
I replaced the air filter a couple of months ago it's clean. I've been running 93 octane because when I didn't I could feel a knock in the engine. The 3.5l is a high compression engine I've been told and needs premium fuel. It has about 85k miles so I don't think there is a timing issue and I've never had a miss or anything. It runs fine I'm just concerned cause I haven't had this pathfinder for more than 48 hours without a ses light coming on. They fixed and replaced a ton of parts. It has a new throttle body, actually 2 since I got it as the one was defective.
Re: p0172 problem
Compression ratio higher than 9:1, try using lower than 93 octane and verify your engine requires high octane because if it does not you are:
wasting money
Carbon fouling your engine
Take a peek inside to the throttle plate. If dark with carbon it needs cleaning. Buy an upper lube for that engine and see if it helps, the MIL light can be reset and see if it returns the same code.
An engine carboned up will have high compression because the carbon deposits take up space.
You could do a Seafoam cleansing but if you are truly carboned up I suggest a gently easy cleaning by using the Seafoam in your gas tank to work over time instead of a blast of it and tons of smoking releasing carbon products that may cause other problems.
When hot does your car run on as if dieseling when shut down?
Try lowering the octane rating a bit at a time to see where and what condition that 3.5 is in and make sure the static timing is where it belongs and make sure the advance system does advance the timing all the way at high speed. Your manual will give the advance readings and a timing light will give you a visual of the advancing mechanism.
wasting money
Carbon fouling your engine
Take a peek inside to the throttle plate. If dark with carbon it needs cleaning. Buy an upper lube for that engine and see if it helps, the MIL light can be reset and see if it returns the same code.
An engine carboned up will have high compression because the carbon deposits take up space.
You could do a Seafoam cleansing but if you are truly carboned up I suggest a gently easy cleaning by using the Seafoam in your gas tank to work over time instead of a blast of it and tons of smoking releasing carbon products that may cause other problems.
When hot does your car run on as if dieseling when shut down?
Try lowering the octane rating a bit at a time to see where and what condition that 3.5 is in and make sure the static timing is where it belongs and make sure the advance system does advance the timing all the way at high speed. Your manual will give the advance readings and a timing light will give you a visual of the advancing mechanism.
Re: p0172 problem
I haven't run a timing light on it yet I have one at the house, I'll check the timing when I get home from work. Unfortunately I didn't get a manual with my pathfinder as I bought it used. I bought an aftermarket Haynes manual which does a full breakdown of the vehicle and at least gives me something to go by. I'm very leery about doing anything with the throttle body as it is new and it's wire driven. I don't have the tools to do a proper idle air relearn, and I know you can do a manual one but it's a royal pain. I've never heard of seafoam, the engine is very clean practically no rust of anything. That doesn't mean there isn't some carbon buildup within. However, do you think that would be the problem causing the engine to run rich?
Re: p0172 problem
Rich condition is built in to ECM (CPU) but more a programmable controller than a processing unit and takes into account the "Stoichiometric or ideal condition of fuel to air for proper combustion. This ideal ratio is 14.6 to 1, 14.6:1 with air providing oxygen and fuel being gasoline. By volume there is 14.6 x more air than fuel and if the amount of air drops or the amount of fuel increases the ratio changes.
Too lean results in a higher over all temperature, destroying plugs, valves, springs, and combustion chambers
Too rich is opposite but bad also in that the condition fouls plugs, creates carbon deposits and cools combustion and destroys MPG.
Both conditions are expensive and bad for the engine.
The causes related in previous posts but can be created by the fuel your using. If you do not want to change octane ratings at least change where you are getting fuel, just an experiment. The vehicle has little history with you so you are going to have to experiment.
A new throttle body is assumed to be good, remove the conduits feeding it and look. If your system is by wire instead of springs, cable it should be easier to view. If you are not good with tools take pictures.
You must correct the condition that creates a coded DTC, trouble. A rich condition is the use of excess fuel by using too much fuel or starving air which contains the O2 levels. How long has this car be running rich...if you do not know take a look at the end of the tail pipe. Is it black with soot deposits. If so the rich mixture has worked through the engine to the catalytic converter, through that and to the end, but along the way both O2 sensors before and after the converter are covered with carbon and likely they are slow to change your mixture ratio while you drive.
At this point the engine may not be carbon prone but the O2 sensors have been covered with carbon and the overall picture of the exhaust is too much fuel deposits so the ratio is out and CPU are dumb enough to interpret that as too rich. All because the rich condition covered the O2 sensors.
The other choice if you do not want to pursue this problem is to pay someone to fix it.
But whether you do it or a paid professional you both must investigate the causes and now the effects.
Check the tail pipe
If clean then pull the O2 sensors.
Try cleaning the end or replace
Look in the mouth of the throttle body, carbon any where if so clean
Remember that the ECU gets input from the sensors, check the sensors, not very often the ECU is bad...but it happens...check the obvious...the easiest then clue us in.
Too lean results in a higher over all temperature, destroying plugs, valves, springs, and combustion chambers
Too rich is opposite but bad also in that the condition fouls plugs, creates carbon deposits and cools combustion and destroys MPG.
Both conditions are expensive and bad for the engine.
The causes related in previous posts but can be created by the fuel your using. If you do not want to change octane ratings at least change where you are getting fuel, just an experiment. The vehicle has little history with you so you are going to have to experiment.
A new throttle body is assumed to be good, remove the conduits feeding it and look. If your system is by wire instead of springs, cable it should be easier to view. If you are not good with tools take pictures.
You must correct the condition that creates a coded DTC, trouble. A rich condition is the use of excess fuel by using too much fuel or starving air which contains the O2 levels. How long has this car be running rich...if you do not know take a look at the end of the tail pipe. Is it black with soot deposits. If so the rich mixture has worked through the engine to the catalytic converter, through that and to the end, but along the way both O2 sensors before and after the converter are covered with carbon and likely they are slow to change your mixture ratio while you drive.
At this point the engine may not be carbon prone but the O2 sensors have been covered with carbon and the overall picture of the exhaust is too much fuel deposits so the ratio is out and CPU are dumb enough to interpret that as too rich. All because the rich condition covered the O2 sensors.
The other choice if you do not want to pursue this problem is to pay someone to fix it.
But whether you do it or a paid professional you both must investigate the causes and now the effects.
Check the tail pipe
If clean then pull the O2 sensors.
Try cleaning the end or replace
Look in the mouth of the throttle body, carbon any where if so clean
Remember that the ECU gets input from the sensors, check the sensors, not very often the ECU is bad...but it happens...check the obvious...the easiest then clue us in.
Re: p0172 problem
I have a new ecu, and throttle body due to a high idle problem. Then after those were replaced by the dealers mechanic I began to get the p0172 warning. He then replaced the O2 sensor, MAF sensor, and put a new injector in cause the warning kept coming on. He ran the vehicle with his computer attached and determined the O2 sensor was bad, as for the MAF sensor it was a common problem so he just replaced it figuring it would fix the problem, it didn't. Then put in a new injector after checking the fuel regulator like I told him too. I'm not paying for any of this since this car hasn't been right and won't pass NY state inspection since I got it from the dealer. I was just looking for suggestions on where I could possibly lead this mechanic as usually when running rich it's an O2 sensor, MAF sensor, fuel regulator or injector. As all of those have been exhausted my knowledge doesn't extend much beyond that. I will probably be taking the car back again... this has been going on for over 4 months, and the dealer had the car for at least 2 months of that, and took it to many mechanics and the Nissan dealer for the computer. It's been quite a headache for me as I've always worked on my own vehicle but don't feel responsible for fixing a car I just bought. It should be perfect for a while after leaving the dealer, used vehicle or not. Thanks for your input, I'll see what I can see on my own, and hopefully this will get resolved soon. I really like the vehicle otherwise I would've made the dealer refund my money by now, and he's always given me a car to drive while it's being worked on.
Re: p0172 problem
You may have to take up the no work no deal approach. You must have had a miss fire on the injector that was replaced, otherwise how did he know what injector? At this time now knowing what is happening tell them to replace the complete fuel input system, fuel filter to injectors. If not get your money back and look at something else.
A car is for travel not to spend time fixing. Good luck, even if they fix it what's next, history is needed when purchasing used!
A car is for travel not to spend time fixing. Good luck, even if they fix it what's next, history is needed when purchasing used!