maf sensor

I know theis is a toyota forum, but I need your opnion on my wife's 01
Nissan pathfinder.

I just replaced the upstream O2 sensor on my wife's 01 pathfinder. after a
week of driving, the SES light came on again with the same code. P0171. I
reset it and the light came on again and I brought it to the mechanic.

They said it's the MAF sensor. and the code was P0170.
is it possible for the MAF sensor to trigger a P0171 and a P0170?

and if the MAF sensor is really bad, what are the long term effects if I
don't replace it?

thanks.

"Raymond" <noemail@noemail.com> wrote in message
news:JrB2f.40$5r6.2577@news.uswest.net...[color=blue]
>I know theis is a toyota forum, but I need your opnion on my wife's 01
> Nissan pathfinder.
>
> I just replaced the upstream O2 sensor on my wife's 01 pathfinder. after a
> week of driving, the SES light came on again with the same code. P0171. I
> reset it and the light came on again and I brought it to the mechanic.[/color]

It sounds like you have an OBD II code scanner. When you scan codes, always
scroll the display down to check for multiple codes before clearing the
codes. Codes will be listed from lowest number to highest number.
[color=blue]
>
> They said it's the MAF sensor. and the code was P0170.[/color]

If the P0170 code was in there before, it should have shown up before the
P0171 code. By the way, P0170 means that there is a fuel trim malfunction
for bank 1. P0171 means that the system is too lean for bank 1

DTC's related to the Mass Air Flow sensor are codes P0100 through P0104.
[color=blue]
> is it possible for the MAF sensor to trigger a P0171 and a P0170?[/color]

Yes, although I'd suspect the O2 sensor before a MAF sensor, especially if
there is not MAF trouble code. What kind of O2 sensor did you install? Is
it OEM or aftermarket? Have you considered the possibility that the
replacement O2 sensor is bad or incorrect? Have you checked the wiring and
plugs for the O2 sensor?[color=blue]
>
> and if the MAF sensor is really bad, what are the long term effects if I
> don't replace it?
>
> thanks.
>[/color]
If a MAF sensor is bad, it could set a trouble code or make the system run
so lean or rich that the O2 sensor cannot compensate for it in closed loop
operation.
--
Ray O
correct the return address punctuation to reply

"Ray O" <rokigawa@tristarassociatesDOT.com> wrote in message
news:78b7f$434b4efd$180fead6$6831@msgid.meganewsservers.com...[color=blue]
>
> "Raymond" <noemail@noemail.com> wrote in message
> news:JrB2f.40$5r6.2577@news.uswest.net...[color=green]
> >I know theis is a toyota forum, but I need your opnion on my wife's 01
> > Nissan pathfinder.
> >
> > I just replaced the upstream O2 sensor on my wife's 01 pathfinder. after[/color][/color]
a[color=blue][color=green]
> > week of driving, the SES light came on again with the same code. P0171.[/color][/color]
I[color=blue][color=green]
> > reset it and the light came on again and I brought it to the mechanic.[/color]
>
> It sounds like you have an OBD II code scanner. When you scan codes,[/color]
always[color=blue]
> scroll the display down to check for multiple codes before clearing the
> codes. Codes will be listed from lowest number to highest number.
>[color=green]
> >
> > They said it's the MAF sensor. and the code was P0170.[/color]
>
> If the P0170 code was in there before, it should have shown up before the
> P0171 code. By the way, P0170 means that there is a fuel trim malfunction
> for bank 1. P0171 means that the system is too lean for bank 1
>
> DTC's related to the Mass Air Flow sensor are codes P0100 through P0104.[/color]

ah, I forgot to mention, that the shop said that there was a P0100. I didn't
check it the 2nd time the light came back on. I assumed it was the same
code.[color=blue]
>[color=green]
> > is it possible for the MAF sensor to trigger a P0171 and a P0170?[/color]
>
> Yes, although I'd suspect the O2 sensor before a MAF sensor, especially if
> there is not MAF trouble code. What kind of O2 sensor did you install?[/color]
Is[color=blue]
> it OEM or aftermarket? Have you considered the possibility that the
> replacement O2 sensor is bad or incorrect? Have you checked the wiring[/color]
and[color=blue]
> plugs for the O2 sensor?[/color]
The shop replaced it so I'll have to double check with them the next time I
get the check engine light.
[color=blue][color=green]
> >
> > and if the MAF sensor is really bad, what are the long term effects if I
> > don't replace it?
> >
> > thanks.
> >[/color]
> If a MAF sensor is bad, it could set a trouble code or make the system run
> so lean or rich that the O2 sensor cannot compensate for it in closed loop
> operation.
> --
> Ray O
> correct the return address punctuation to reply
>
>[/color]

On Tue, 11 Oct 2005 09:55:18 -0400, Raymond wrote:


Keep this in your 'toolbox' :

[url]http://www.troublecodes.net/Toyota/[/url]

It indicates p0100 is a 'generic' MAF code. Are there any others, other
than the p0170 and 171?

[color=blue]
>
> "Ray O" <rokigawa@tristarassociatesDOT.com> wrote in message
> news:78b7f$434b4efd$180fead6$6831@msgid.meganewsservers.com...[color=green]
>>
>> "Raymond" <noemail@noemail.com> wrote in message
>> news:JrB2f.40$5r6.2577@news.uswest.net...[color=darkred]
>> >I know theis is a toyota forum, but I need your opnion on my wife's 01
>> > Nissan pathfinder.
>> >
>> > I just replaced the upstream O2 sensor on my wife's 01 pathfinder. after[/color][/color]
> a[color=green][color=darkred]
>> > week of driving, the SES light came on again with the same code. P0171.[/color][/color]
> I[color=green][color=darkred]
>> > reset it and the light came on again and I brought it to the mechanic.[/color]
>>
>> It sounds like you have an OBD II code scanner. When you scan codes,[/color]
> always[color=green]
>> scroll the display down to check for multiple codes before clearing the
>> codes. Codes will be listed from lowest number to highest number.
>>[color=darkred]
>> >
>> > They said it's the MAF sensor. and the code was P0170.[/color]
>>
>> If the P0170 code was in there before, it should have shown up before the
>> P0171 code. By the way, P0170 means that there is a fuel trim malfunction
>> for bank 1. P0171 means that the system is too lean for bank 1
>>
>> DTC's related to the Mass Air Flow sensor are codes P0100 through P0104.[/color]
>
> ah, I forgot to mention, that the shop said that there was a P0100. I didn't
> check it the 2nd time the light came back on. I assumed it was the same
> code.[color=green]
>>[color=darkred]
>> > is it possible for the MAF sensor to trigger a P0171 and a P0170?[/color]
>>
>> Yes, although I'd suspect the O2 sensor before a MAF sensor, especially if
>> there is not MAF trouble code. What kind of O2 sensor did you install?[/color]
> Is[color=green]
>> it OEM or aftermarket? Have you considered the possibility that the
>> replacement O2 sensor is bad or incorrect? Have you checked the wiring[/color]
> and[color=green]
>> plugs for the O2 sensor?[/color]
> The shop replaced it so I'll have to double check with them the next time I
> get the check engine light.
>[color=green][color=darkred]
>> >
>> > and if the MAF sensor is really bad, what are the long term effects if I
>> > don't replace it?
>> >
>> > thanks.
>> >[/color]
>> If a MAF sensor is bad, it could set a trouble code or make the system run
>> so lean or rich that the O2 sensor cannot compensate for it in closed loop
>> operation.
>> --
>> Ray O
>> correct the return address punctuation to reply
>>
>>[/color][/color]

the first time it was P0171 & P0174. both upstream oxygen sensors were
replaced.

I'll have to wait again until the light comes back on and I won't assume
that it's the same code.

"Hachiroku" <Trueno@ae86.gts> wrote in message
news:pan.2005.10.11.15.51.12.684905@ae86.gts...[color=blue]
> On Tue, 11 Oct 2005 09:55:18 -0400, Raymond wrote:
>
>
> Keep this in your 'toolbox' :
>
> [url]http://www.troublecodes.net/Toyota/[/url]
>
> It indicates p0100 is a 'generic' MAF code. Are there any others, other
> than the p0170 and 171?
>
>[color=green]
> >
> > "Ray O" <rokigawa@tristarassociatesDOT.com> wrote in message
> > news:78b7f$434b4efd$180fead6$6831@msgid.meganewsservers.com...[color=darkred]
> >>
> >> "Raymond" <noemail@noemail.com> wrote in message
> >> news:JrB2f.40$5r6.2577@news.uswest.net...
> >> >I know theis is a toyota forum, but I need your opnion on my wife's 01
> >> > Nissan pathfinder.
> >> >
> >> > I just replaced the upstream O2 sensor on my wife's 01 pathfinder.[/color][/color][/color]
after[color=blue][color=green]
> > a[color=darkred]
> >> > week of driving, the SES light came on again with the same code.[/color][/color][/color]
P0171.[color=blue][color=green]
> > I[color=darkred]
> >> > reset it and the light came on again and I brought it to the[/color][/color][/color]
mechanic.[color=blue][color=green][color=darkred]
> >>
> >> It sounds like you have an OBD II code scanner. When you scan codes,[/color]
> > always[color=darkred]
> >> scroll the display down to check for multiple codes before clearing the
> >> codes. Codes will be listed from lowest number to highest number.
> >>
> >> >
> >> > They said it's the MAF sensor. and the code was P0170.
> >>
> >> If the P0170 code was in there before, it should have shown up before[/color][/color][/color]
the[color=blue][color=green][color=darkred]
> >> P0171 code. By the way, P0170 means that there is a fuel trim[/color][/color][/color]
malfunction[color=blue][color=green][color=darkred]
> >> for bank 1. P0171 means that the system is too lean for bank 1
> >>
> >> DTC's related to the Mass Air Flow sensor are codes P0100 through[/color][/color][/color]
P0104.[color=blue][color=green]
> >
> > ah, I forgot to mention, that the shop said that there was a P0100. I[/color][/color]
didn't[color=blue][color=green]
> > check it the 2nd time the light came back on. I assumed it was the same
> > code.[color=darkred]
> >>
> >> > is it possible for the MAF sensor to trigger a P0171 and a P0170?
> >>
> >> Yes, although I'd suspect the O2 sensor before a MAF sensor, especially[/color][/color][/color]
if[color=blue][color=green][color=darkred]
> >> there is not MAF trouble code. What kind of O2 sensor did you install?[/color]
> > Is[color=darkred]
> >> it OEM or aftermarket? Have you considered the possibility that the
> >> replacement O2 sensor is bad or incorrect? Have you checked the wiring[/color]
> > and[color=darkred]
> >> plugs for the O2 sensor?[/color]
> > The shop replaced it so I'll have to double check with them the next[/color][/color]
time I[color=blue][color=green]
> > get the check engine light.
> >[color=darkred]
> >> >
> >> > and if the MAF sensor is really bad, what are the long term effects[/color][/color][/color]
if I[color=blue][color=green][color=darkred]
> >> > don't replace it?
> >> >
> >> > thanks.
> >> >
> >> If a MAF sensor is bad, it could set a trouble code or make the system[/color][/color][/color]
run[color=blue][color=green][color=darkred]
> >> so lean or rich that the O2 sensor cannot compensate for it in closed[/color][/color][/color]
loop[color=blue][color=green][color=darkred]
> >> operation.
> >> --
> >> Ray O
> >> correct the return address punctuation to reply
> >>
> >>[/color][/color]
>[/color]

"Ray O" <rokigawa@tristarassociatesDOT.com> wrote in message
news:78b7f$434b4efd$180fead6$6831@msgid.meganewsservers.com...[color=blue]
>
> "Raymond" <noemail@noemail.com> wrote in message
> news:JrB2f.40$5r6.2577@news.uswest.net...[color=green]
> >I know theis is a toyota forum, but I need your opnion on my wife's 01
> > Nissan pathfinder.
> >
> > I just replaced the upstream O2 sensor on my wife's 01 pathfinder. after[/color][/color]
a[color=blue][color=green]
> > week of driving, the SES light came on again with the same code. P0171.[/color][/color]
I[color=blue][color=green]
> > reset it and the light came on again and I brought it to the mechanic.[/color]
>
> It sounds like you have an OBD II code scanner. When you scan codes,[/color]
always[color=blue]
> scroll the display down to check for multiple codes before clearing the
> codes. Codes will be listed from lowest number to highest number.
>[color=green]
> >
> > They said it's the MAF sensor. and the code was P0170.[/color]
>
> If the P0170 code was in there before, it should have shown up before the
> P0171 code. By the way, P0170 means that there is a fuel trim malfunction
> for bank 1. P0171 means that the system is too lean for bank 1
>
> DTC's related to the Mass Air Flow sensor are codes P0100 through P0104.
>[color=green]
> > is it possible for the MAF sensor to trigger a P0171 and a P0170?[/color]
>
> Yes, although I'd suspect the O2 sensor before a MAF sensor, especially if
> there is not MAF trouble code. What kind of O2 sensor did you install?[/color]
Is[color=blue]
> it OEM or aftermarket? Have you considered the possibility that the
> replacement O2 sensor is bad or incorrect? Have you checked the wiring[/color]
and[color=blue]
> plugs for the O2 sensor?[color=green]
> >
> > and if the MAF sensor is really bad, what are the long term effects if I
> > don't replace it?
> >
> > thanks.
> >[/color]
> If a MAF sensor is bad, it could set a trouble code or make the system run
> so lean or rich that the O2 sensor cannot compensate for it in closed loop
> operation.[/color]

if the MAF sensor is bad, will I notice it with how the engine runs?

can the MAF sensor be partially working like the O2 sensors? or is it always
either good or bad?
[color=blue]
> --
> Ray O
> correct the return address punctuation to reply
>
>[/color]

"Raymond" <noemail@noemail.com> wrote in message
news:EKR2f.36$gz6.1506@news.uswest.net...[color=blue]
>
> "Ray O" <rokigawa@tristarassociatesDOT.com> wrote in message
> news:78b7f$434b4efd$180fead6$6831@msgid.meganewsservers.com...[color=green]
>>
>> "Raymond" <noemail@noemail.com> wrote in message
>> news:JrB2f.40$5r6.2577@news.uswest.net...[color=darkred]
>> >I know theis is a toyota forum, but I need your opnion on my wife's 01
>> > Nissan pathfinder.
>> >
>> > I just replaced the upstream O2 sensor on my wife's 01 pathfinder.
>> > after[/color][/color]
> a[color=green][color=darkred]
>> > week of driving, the SES light came on again with the same code. P0171.[/color][/color]
> I[color=green][color=darkred]
>> > reset it and the light came on again and I brought it to the mechanic.[/color]
>>
>> It sounds like you have an OBD II code scanner. When you scan codes,[/color]
> always[color=green]
>> scroll the display down to check for multiple codes before clearing the
>> codes. Codes will be listed from lowest number to highest number.
>>[color=darkred]
>> >
>> > They said it's the MAF sensor. and the code was P0170.[/color]
>>
>> If the P0170 code was in there before, it should have shown up before the
>> P0171 code. By the way, P0170 means that there is a fuel trim
>> malfunction
>> for bank 1. P0171 means that the system is too lean for bank 1
>>
>> DTC's related to the Mass Air Flow sensor are codes P0100 through P0104.
>>[color=darkred]
>> > is it possible for the MAF sensor to trigger a P0171 and a P0170?[/color]
>>
>> Yes, although I'd suspect the O2 sensor before a MAF sensor, especially
>> if
>> there is not MAF trouble code. What kind of O2 sensor did you install?[/color]
> Is[color=green]
>> it OEM or aftermarket? Have you considered the possibility that the
>> replacement O2 sensor is bad or incorrect? Have you checked the wiring[/color]
> and[color=green]
>> plugs for the O2 sensor?[color=darkred]
>> >
>> > and if the MAF sensor is really bad, what are the long term effects if
>> > I
>> > don't replace it?
>> >
>> > thanks.
>> >[/color]
>> If a MAF sensor is bad, it could set a trouble code or make the system
>> run
>> so lean or rich that the O2 sensor cannot compensate for it in closed
>> loop
>> operation.[/color]
>[/color]

First of all, don't assume that the trouble code is the same if the check
engine light comes on again.
[color=blue]
> if the MAF sensor is bad, will I notice it with how the engine runs?[/color]

Maybe but I doubt it unless the MAF sensor is in really bad shape.
[color=blue]
>
> can the MAF sensor be partially working like the O2 sensors? or is it
> always
> either good or bad?
>[color=green]
>> --
>> Ray O
>> correct the return address punctuation to reply
>>[/color][/color]
MAF sensor operation can be marginal, not bad enough to set a code that the
MAF sensor is inoperative but still not giving good info to the ECU.

All this is speculation until you get another check engine light.
--
Ray O
correct the return address punctuation to reply