TonY_G

Hi guys, i have a serious problem thats driving me nuts.

I have a 2000 gs400,

I was due for an emission test and car won't pass.
I have CEL light on..
I got the Code P0125 Temperature For Closed Loop Fuel Control

Things i have just replaced in the last 2 weeks:

I replaced all 4 o2 sensors with Denso OEM that i bought from lexus,
I replaced both magnaflow High flow cats i had, figuring it could be that.
I replaced the SRT air filter with AEM dryflow
I just changed OIL with Amsoil 10w30
I put guarantee to pass solution(injector cleaner/fuel line etc) with full tank of premium and i wasted a tank full already.
I replaced spark plugs like 10k ago with denso as well,


I scanned the car and this code P0125 is still on.... The car runs good, i can't seem to figure out whats going on.

I have 125k on my car right now
Only thing i haven't changed is Fuel fitler and injectors, can it be either one of these two things that is possibly causing this engine code? or could it be something else?

I have spent close to $1000 already in trying to fix this, but still wont got away...

please help!

GS300ToM

iTrader: (32)

have u check if u car goes in closed loop with a scanner?? Coolant temp sensor will casuse this as well

macd7919

iTrader: (10)

Who suggested changing all those things?

None of the things you changed has anything to do with temperature that would throw a check engine light. It is most likely your coolant temp sensor is malfunctioning. If it was a mechanic recommending you change all that stuff I would look for a new mechanic as they just wasted a lot of your money.

GS300ToM

iTrader: (32)

yes sir!!!! first thing first.... close loop deals with o2 not working or cts malfunction

TonY_G

Ok thank you guys for your input,

so i will look into coolent temp sensor and see if that solves the problem.

I replaced coolent and thermostat about 6 months ago so could that do anything with this code as well?

so is my car in danger right now? coolent not getting hot enough?

macd7919

iTrader: (10)

No, the coolant and thermostat wouldn't help. The coolant temp sensor just measures how hot the coolant is getting. If the sensor isn't working properly it is telling the car that the coolant isn't ever getting hot so the car is operating in a "cold" condition even though the coolant is really up to temp.

TonY_G

Hey bro, so you think based on what i told you, its that? just the sensor?

some people told me A/F? or fuel filter?

TonY_G

really appreciate your help,
thank you once again...

TonY_G

so possible things:
in list of what it could be........

1) coolent temp sensor
2) A/F sensor? <-----is this o2 sensor?
3) fuel filter?
4) injectors?

all these could cause P0125?

macd7919

iTrader: (10)

Do the coolant temp sensor first. The other things you have listed all have to do with the air fuel mixture in one way or the other but none of them will affect the temperature readings. I'm 99% sure it will be fixed with the coolant temp sensor.

The reason people may have guided you to those other things would be because the car will run a different A/F ratio when in closed loop or open loop. The readings of the O2 sensors are based because of what loop the car is running in, not causing the car to run that way. The coolant temp sensor causes the car to run in a certain loop. Make sense? Basically you started at point Z(O2 sensors) and worked your way back to point A (coolant temp sensor).

The people who were telling you to do the O2 sensors and everything else probably have good intentions but the fact that the code is a Temperature for Closed loop Fuel Control should have tipped them off it wasn't a mixture problem from the get go, would have saved you a lot of money.

Hate to say it but this is probably all you needed. $35 and about 30 minutes of time.

Coolant Temp Sensor

Though you may prefer to pick up a Oem version.

TonY_G

thank you for your input man, i really appreciate it.

I will go to lexus tomorrow and buy that part.

Can i install it myself? is it plug n play kinda thing? or i have to take it to a shop?

I know it is on the drivers side, behind the oil dipstick or around there somewhere..

macd7919

iTrader: (10)

Yes it's mostly a plug and play type thing. You will probably want to have some rags around and the car completely cooled off before removing it. I'm pretty sure this should solve your problem.

GS4_Fiend

iTrader: (22)

Very well said. Keeping it simple. Don't overwhelm yourself with complicity.

TonY_G

update...

So i went into lexus today.. they told me that there are 3 types of coolent temp sensor and i need to know which one I need.

Told me..there's a EFI coolent Temp Sensor, (i think i need this one)
There's one on the rad..and there's another one as well..

can some one please give me the part # i need to give to these guys?
I don't wanna order the wrong part and these guys seem clueless!

GS300ToM

iTrader: (32)

cant say any more better than that haha!!!!! u said u replaced your cats, how much that ran yo pockets?