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CEL code 25 Need Help please.

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Old 10-30-2008 | 05:48 AM
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slcpunk74's Avatar
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From: SL,UT
CEL code 25 Need Help please.

I just bought this 94 yoda prerunner with the 3.0(I know) 5spd 4x4 yata yata

anywho it has been burning oil and smoking on startup here and there but just recently the check engine light would come on and it runs a bit off in the lower rpms and wont smooth out till about 2500. I did the self diagnose and it came up with a code 25...

I just changed the plugs and they had a little oil on them(obvious) and they also looked rich. I was reading up on what the code 25
AIR/FUEL RATIO LEAN INDICATOR--LEAN SIGNAL SENT TO ECU FROM O2 SENSOR
--INJECTOR FAULT(S)

--FUEL PRESSURE

--OXYGEN SENSOR

--AIRFLOW METER OR MAP SENSOR

--IGNITION

--ECU

so the only thing I can think of is that maybe this oil I am burning is making my o2 senor hate life and that is why it is rich..?

I am sure you guys have many good thoughts on this thanks
Old 10-30-2008 | 06:10 AM
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From: ct
check your maf. can make for a lot of problems if bad
Old 10-30-2008 | 11:06 AM
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how do I check maf?

I forgot to mention but when I reset the computer it runs good for a while till the light comes back on
Old 10-30-2008 | 11:08 AM
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From: Abington, PA
Check up on my thread...lots of good info there if your truck is doing the same thing mine is:
https://www.yotatech.com/forums/f116...k-gear-150667/
Old 10-30-2008 | 11:28 AM
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From: Temecula Valley, CA
code 25 is air-fuel ratio lean (not rich)
possible causes:
engine ground bolt loose
E1 circuit open
injector circuit / injector
fuel pressure low
VAF meter malfunction
PAIR system malfunction
Heated O2 sensor heater circuit malfunction
O2 sensor malfunction
Ignition system (timing, etc.)
ECM (ECU) malfunction
Old 10-30-2008 | 11:41 AM
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From: Abington, PA
Originally Posted by abecedarian
code 25 is air-fuel ratio lean (not rich)
possible causes:
engine ground bolt loose
E1 circuit open
injector circuit / injector
fuel pressure low
VAF meter malfunction
PAIR system malfunction
Heated O2 sensor heater circuit malfunction
O2 sensor malfunction
Ignition system (timing, etc.)
ECM (ECU) malfunction
You must have this bookmarked somewhere for n00bs like me :bats eyes:
Old 10-30-2008 | 12:33 PM
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From: ct
you can try unplugging the maf and see if it still runs or runs better. when they go bad they can cause the vehicle to run way too lean or too rich. make sure the intake tube isn't broken after the maf
Old 10-30-2008 | 04:25 PM
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slcpunk74's Avatar
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From: SL,UT
Originally Posted by abecedarian
code 25 is air-fuel ratio lean (not rich)
possible causes:
engine ground bolt loose
E1 circuit open
injector circuit / injector
fuel pressure low
VAF meter malfunction
PAIR system malfunction
Heated O2 sensor heater circuit malfunction
O2 sensor malfunction
Ignition system (timing, etc.)
ECM (ECU) malfunction
I do understand that the code says it would be lean but I also stated that to the contrary the plugs looked rich... That is why I was confused.
Old 10-30-2008 | 04:26 PM
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From: SL,UT
Originally Posted by turyota90
you can try unplugging the maf and see if it still runs or runs better. when they go bad they can cause the vehicle to run way too lean or too rich. make sure the intake tube isn't broken after the maf
I will give this a try and no the intake is not broken.
Old 10-30-2008 | 06:53 PM
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From: milwaukee, WI baby muddin in the streets!!
if the o2 is telling the ecu im lean the ecu will over inrich the motor to make the o2 happy but if the o2 is stuck on lean then its just going to get richer and richer get my drift

if you wanna check out the o2 get a multimeter its going to be your friend start your rig get it wormed up unplug the o2 with motor running and test it make sure you do it to spec like they tel you in the fsm if she goes low in volts to high in volts you know the o2 is fine if it stays low or high then you know the o2 dumbed out on ya

hope it helps in my rig i have a air/fuel gauge on the piller so i can gheck on the fly and i know if thers something wrong
Old 10-30-2008 | 06:53 PM
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From: milwaukee, WI baby muddin in the streets!!
oh and by the way nice location you got there buddy lol
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