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View Full Version : OBDII codes P0171 & P0170 Need Help!!!



scout68
01-11-2007, 01:07 PM
Hello. Newbie here. I have searched the posts but cant find much related to my problem. I have a 1999 Honda Accord (4cyl, VTEC, 5spd, 179K miles, bone stock...no mods) that keeps throwing codes P0171 and P0170. It runs like a top but wants to chug just a bit when cold, like its not getting enough gas. When I clear the code it stays out for a few days and then pops back on and then stays on. I have noticed that it is more inclined to come on when I have others riding with me (heavier load). I have looked for vacuum leaks and have found none. I cant afford to throw money at it and can do most of the work myself if I could get some idea of the problem. Is this a common problem with the Hondas? Is there a "more likely than others" solution? O2? Fuel Regulator? How do I go about checking for any possible fix? Any help would be greatly appreciated!!!

Xfactor
01-17-2007, 09:56 PM
Hey man, I have a 98 Accord and mine does the same thing. It was fine until I took it to emmisions to have it checked(they rape cars), as soon as I drove it home my check engine light turned on. I checked but no codes flashed, so I reset it. It was fine for about 2 weeks and then it turned on again. I think that it might be common for accords to throw the light on because my buddy who has a 98 v6 always has his pop up on him. Sorry I know it doesn't really help your situation, but just letting you know that you're not alone:)

gotnoname
01-18-2007, 08:34 PM
P0171 is the code for "fuel system too lean" and im not too sure what code P0170. that code normally comes up when there is moisture in the fuel pressure regulator. best way to fix it is to replace the fuel pressure regulator

bryanb124
01-28-2007, 02:10 PM
To solve this problem you have to understand how it occured. Most folks who end up with this problem happen to have a K&N air filter or someother high flow air filter. The culprit is the oil from the filter contaminating the Mass Air Flow Sensor. They over oil the filter and some of this ends up getting on the MAF sensor just downwind of the air box. This small sensor determines the flow of air coming in to the engine. When this gets dirty it reads incorrectly throwing the CEL (Check Engine Light) for 0171.

Regardless if you have one of these air filters or not here is the fix:

1) Replace your airfilter.

2) Pickup a can of electrical contact cleaner at your local automotive store.

3) Disconnect the airhose from the airbox to access the MAF.

4) Liberally spray the contact cleaner over all of the the MAF.

5) DO NOT TOUCH THE MAF WITH ANYTHING (i.e. qtips, rags, etc. you will just make it worse).

6) Wipe out the airhose interior surfaces as well as the airbox downwind of the airfilter.

7) Reset your CEL with a diagnostic tool or go to a parts store, they will do it for free when they read your codes.

8) Put everything back together....you are done.

9) If the CEL comes back on you most likely need a new MAF, but should probably have this diagnosted by a pro...dont get a new one, just get one from a boneyard and clean it as described above.

Best of Luck

Bryan

gotnoname
01-28-2007, 08:05 PM
To solve this problem you have to understand how it occured. Most folks who end up with this problem happen to have a K&N air filter or someother high flow air filter. The culprit is the oil from the filter contaminating the Mass Air Flow Sensor. They over oil the filter and some of this ends up getting on the MAF sensor just downwind of the air box. This small sensor determines the flow of air coming in to the engine. When this gets dirty it reads incorrectly throwing the CEL (Check Engine Light) for 0171.

im not saying that info is wrong, but im sure that code 0171 isnt for a MAR sensor

bryanb124
01-28-2007, 09:21 PM
With all due disrespect, just because I have a total of one post on this forum does not make me wrong...

Go to this link and have the sense to know what you are talking about before you post (thats good advice on any forum):

http://www.obd-codes.com/trouble_codes/generic/p0171-system-too-lean-bank-1-oxygen-sensor.php

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P0171 OBD-II Trouble Code

Technical Description

System Too Lean (Bank 1)

What does that mean?

Basically this means that an oxygen sensor in bank 1 detected a lean condition (too much oxygen in the exhaust). On V6/V8/V10 engines, Bank 1 is the side of the engine that has cylinder #1.

Note: This DTC is very similar to P0174, and in fact your vehicle may show both codes at the same time.

Symptoms

You will more than likely not notice any drivability problems, although there may be symptoms such as a lack of power, detonation (spark knock), and/or a hesitation/surge on acceleration.

Causes

A code P0171 may mean that one or more of the following has happened:

The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters (K&N, etc.) can cause the MAF to become dirty if the filter is over-oiled
There could be a vacuum leak downstream of the MAF sensor.
Possible Solutions

Possible solutions include:

In the vast majority of cases, simply cleaning the MAF sensor does the trick. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling
Inspect all vacuum and PCV hoses, replace if necessary
Check for a dirty fuel filter and proper fuel pressure.

'nuff said.

Bryan

gotnoname
01-29-2007, 08:51 PM
i apoligize, i was only getting my information from a service bulletin from a honda dealership that i worked at. go to any honda dealership, and ask them to look for the bulletin for a 99 accord with the code P0171.

brickdog2000
01-31-2007, 07:35 PM
I have had the same problems before. I ended up replacing my fuel cap and it fixed it. However, I don't know if this will work for you.

builderbob
02-01-2007, 09:53 AM
I can find no reference to code P0170 as it pertains to Hondas. Code P0171 is referenced to "Fuel system too lean". Honda's list from most likely cause to least is as follows: Fuel supply system, Primary O2 sensor, MAP sensor, contaminated fuel, valve clearance, exhaust system. At the mileage that the car has, I would place my bets on a partially clogged fuel filter. No one seems to change those as often as they should, and yours could be original. Even if it doesn't solve the problem it's not a bad idea as far as maintenance goes. Once again, at this mileage, the engine probably burns a bit of oil, so the O2 sensor may be starting to decay and the ECU is interpreting that as a lean mixture. Honda went through MAP sensors like water in the mid '90's, so I wouldn't discount that, either. The MAP sensor or it's passage may be partially blocked with oil residue in the throttle body, so cleaning the throttle body wouldn't be a bad idea either. The other problems are unlikely. The symptoms you describe (stumble when cold or heavily loaded) would point to a lack of fuel, so I would suggest starting with a fuel filter and cleaning the throttle body.
To the best of my knowledge, 4 cylinder fuel injected Honda's have never used a MAF sensor.

Jysselle595
03-27-2008, 11:12 AM
try this site.....you may understand what there talking about...i have the same issue..http://users.skynet.be/MRS/MR/guide/Diagnostics/DI-77.pdf

Jysselle595
03-27-2008, 11:13 AM
http://users.skynet.be/MRS/MR/guide/Diagnostics/DI-77.pdf this sit may help you with the p0170 code

fiveten
03-30-2008, 06:20 PM
P0171 is a lean condition code.

gotnoname is correct, there is a bulliten for a updated vacuum hose routing and replacement of the fuel pressure regulator. Check this first.

Also I have found is that oil will leak onto the the o2 sensor and contaminate it. If that has not happened then you may have a vacuum leak. You are getting too much air into the exhaust. It is difficult to find if you dont have a scanner to look at the st and lt fuel trim.

The leak may be due to an intake manifold gasket, throttle body gasket, vacuum line disconnected, your car has a vacuum operated engine mount, I have seen those go bad and cause a vacuum leak.

good luck, fiveten

jcd1113
05-11-2008, 12:59 PM
i had the same problem and all the resonse you are correct and to tell you the true it hard to pinpoint exactly me i had to change my fuel cap, oxygen sensor . clean the throttle bobby . good luck

chris75644
06-30-2008, 12:00 PM
Hi, I am working on a 1997 accord 2.2. It was getting P0170 & P0171. I changed the o2 sensor on the manifold. It runs great now. It was also stalling on a cold start. It has 200,000 miles.

mike4kz
07-06-2008, 07:38 AM
Here is an "official" Honda's explanation for error P0171. Not much help though... And nothing for P0170.

hxxp://techinfo.honda.com/rjanisis/pubs/AD/P0171TS9V5AA000AN.pdf

girlbali
07-24-2008, 09:05 AM
Someone please help me..
I have 97 accord V6 2.7L. I have 298K miles on it. First RPM was jumping when I am driving so I changed the ignition coil, that fixed that but after that I noticed when I put my car to warm up for min or two the RPM going up and down like I am giving gas but I am not even in the car it doing it by itself and this was winter time, now its summer looks like problem is fixed by itself. Now it is summer it does not do that now I have new problem I just started getting this code P0170 and P0171. So I changed the fuel filter, sparkplugs, wire...tune-up. still same code also same problem after tune-up and filter replace now car is doing crazy thing car runs ok for while but 20miles or so and then if I turn my car off and start my car back up it stall and most of the time it would not start it take me 20-50times (I blowup my starter doing that now I have new starter and I don't want to blow that one up) before I can get back up running and when I do getting running it will stall and wants to shutdown but I keep pressing gas and it will slowly very slowly start running at same time I would hear some kind of knocking noise from under the car where convertor is( I left the driver side door open I heard it thatís how I know this noise) after that noise is gone car runs like nothing happened. I am thinking it might me MAP sensor or O2 but it might be something else. I need help please help me.

4Cylinders
12-18-2008, 12:29 AM
Someone please help me..
I have 97 accord V6 2.7L. I have 298K miles on it. First RPM was jumping when I am driving so I changed the ignition coil, that fixed that but after that I noticed when I put my car to warm up for min or two the RPM going up and down like I am giving gas but I am not even in the car it doing it by itself and this was winter time, now its summer looks like problem is fixed by itself. Now it is summer it does not do that now I have new problem I just started getting this code P0170 and P0171. So I changed the fuel filter, sparkplugs, wire...tune-up. still same code also same problem after tune-up and filter replace now car is doing crazy thing car runs ok for while but 20miles or so and then if I turn my car off and start my car back up it stall and most of the time it would not start it take me 20-50times (I blowup my starter doing that now I have new starter and I don't want to blow that one up) before I can get back up running and when I do getting running it will stall and wants to shutdown but I keep pressing gas and it will slowly very slowly start running at same time I would hear some kind of knocking noise from under the car where convertor is( I left the driver side door open I heard it thatís how I know this noise) after that noise is gone car runs like nothing happened. I am thinking it might me MAP sensor or O2 but it might be something else. I need help please help me.



Alright the problem with the reving up in down... this most often occurs when it is cold. It is typically caused by a faulty OR a dirty Idle Air Control Valve. I would always try to remove and clean with an intake cleaner or brake cleaner. Let try and replace. Generally this will correct the problem. If not, buy a new one from Advance. Thats probably what's throwing up the P0171 (system too lean) code. MAP sensor is also possible but not the most likely. Replace the IAC first. Hope it helps.

4Cylinders
Service Manager- ASE certified

girlbali
12-20-2008, 04:54 PM
I did exactly what you said about cleaning IAC, but that only took care idle up and down problem. I still had the P0170 and P0171 didn't solve that code. I changed the CAT Converter for that to clear.Thank you for the reply.

mcfatty8
02-01-2009, 11:52 PM
I am also pulling a code P0170 and P0171... Have replaced fuel regulator and thoroughly cleaned intake manifold. This model does not have a Mass Air Sensor or a secondary fuel filter in the engine bay, only in the tank. Any thoughts would be appreciated, map sensor maybe???

mcfatty8
02-10-2009, 07:40 PM
SeaFoam treatment through the brake booster line apparently fixed w/e the problem was... unless Iso-heat works REALLY FAST and it was just water getting into the fuel regulator again. If any of you have tried all this stuff, particularly just cleaning out the easily accessible portions of the intake, I recommend a SeaFoam treatment because worse case scenario is you don't get a cheap fix.

If you've never done it before the best way to do it is as follows.

Park/Neutral Idle...
Remove brake booster line (rear-right portion of engine bay on the firewall(black hemispherical thing))
get a straw or smaller hose to insert into the brake booster line(not so small it gets sucked in(not needed)
SLOWLY let the vacuum suck up about half a can maybe a little more of the SeaFoam
again there is no rush here whatsoever
Shut off the engine and wait 5-10
re-attach the brake booster line
Start engine (may require a little initial revving)
hold RPMs around 3k for about five min occasionally revving to red-line(if you have v-tec its around 4.5k w/o a load so don't try to rev past)
let it idle for a while or drive regularly wherever and your done
you may also add the rest to your gas tank to clean the injectors(before during or after treatment)

adam211minn
07-28-2009, 07:49 AM
P0171 is the code for "fuel system too lean" and im not too sure what code P0170. that code normally comes up when there is moisture in the fuel pressure regulator. best way to fix it is to replace the fuel pressure regulator

I had the exact problems as "Scout68" and after alot of reading and on other forums i came to the same conclusion as "gotnoname". I replaced the fuel pressure regulator which comes with a breather tube re-routing kit. (Found the instructions for routing by typing the tube kit part number in on google) and cleaned the throttle body and all my problems were fixed. now the car runs great!

99' Honda Accord EX, AT

kamathvivek
10-07-2010, 11:19 PM
Hi,

I drive a 2005 Honda Accord LX and got an oil chnage done 2 days ago (10/4/2010).
the check engine light came up today morning. Went to autozone and got the code read for free.
Went to Midas, where i had got my oil chnag done. They were nice enough to check the car again and found some kinfd of vacuum tube was not connected. They suspect it may have come of during the oil chnage.
Fixed it and reset the light. Hopefully things will be fine from here.

gargamel647
10-15-2010, 12:38 PM
90% of the p0171 that we see at the dealership are from people putting e85 or poor quality fuel in the cars. The p0170 code is not a Honda diag code and it was probably pulled with an aftermarket scanner instead of the Honda HDS. The GM p0170 is a o2 bank 1 failure. Troubleshoot the p0171 code. I've never replaced a map or baro sensor in 12 years. If it isn't the fuel your putting into the car then I would look at fuel pressure, test the regulator and test for a bias A/F sensor and o2 sensor. Usually when the regulator is bad you'll know it because the car has a hard time running. The regulator spits out fuel from the vacuum line when disconnected. after market catalytic converters and 02 sensors can also cause this code b/c the placement of the rear sensor is wrong and it gets false reading. Happy hunting!

Pmaster
03-15-2012, 11:31 AM
Hello. Newbie here. I have searched the posts but cant find much related to my problem. I have a 1999 Honda Accord (4cyl, VTEC, 5spd, 179K miles, bone stock...no mods) that keeps throwing codes P0171 and P0170. It runs like a top but wants to chug just a bit when cold, like its not getting enough gas. When I clear the code it stays out for a few days and then pops back on and then stays on. I have noticed that it is more inclined to come on when I have others riding with me (heavier load). I have looked for vacuum leaks and have found none. I cant afford to throw money at it and can do most of the work myself if I could get some idea of the problem. Is this a common problem with the Hondas? Is there a "more likely than others" solution? O2? Fuel Regulator? How do I go about checking for any possible fix? Any help would be greatly appreciated!!!

I hope this helps someone with a hesitation when the car is cold that goes away after it warms up. I tried replacing the MAF, Air intake temp sensor, cleaning the throttle body, sea foam, 3 different types of spark plugs. The mechanic twice (misdiagnosed) light came back on ten minutes after i picked it up. For me it was the bank 1 O2 sensor. I went ahead and replaced both since the back was only $25. Got both from Amazon for about $75.00. Took me 20 min to put em in and my car running better than ever. Can't believe how bad it was running before.