LadyRX300

Hi, I have a 2000 Lexus RX300 and a week ago the CEL and TRAC off light came on I took it to NAPA, AutoZone, and to two different mechanics and they all gave me codes P1130 & P1135.. I called Oxygensensors.com and they told me I needed to change Oxygen Sensor (B1S1) and so I did sunday, but right after my father replaced it, I took it for a test drive and the CEL light came on again I took it to AutoZone again and now a different code came up P0125. Can somebody please tell me what could be wrong?.. does it have to do with replacing the Sensor (B1S1).

lexus114

Okay,The bank 1,sensor 1 sensor is an A/F (air flow sensor) not o2 sensor.Their is only an o2 sensor post the catyletic converter.The P0125 code looks to be;Insufficient coolant temperature for closed loop fuel control.Possibly your coolant temp sensor.I need to do more research on this code for you.

lexus114

Take a look at this;www.obd-codes.com

lexus114

Technical Description

Insufficient Coolant Temperature For Closed Loop Fuel Control
What does that mean?

This means that the engine coolant temperature (ECT) sensor indicates that the engine has not reached the required temperature level to enter closed-loop operation within a specified amount of time after starting the engine.

Symptoms

You will likely not notice any drivability problems.
Causes

A code P0125 may mean that one or more of the following has happened:

* Insufficient warm up time
* Low engine coolant level
* Leaking or stuck open thermostat
* Faulty coolant temperature sensor

Possible Solutions

The simplest thing to do is to reset the code and see if it comes back.

If the code comes back, the problem is likely going to be the result of the above causes (faulty thermostat, faulty coolant sensor, or a low coolant level).
Related P0125 forum topics

* P0125 2000 Galant V6
* 1996 Toyota Corolla P0125
* 2003 vibe P0125 code
* 96 Nissan Maxima P0125
* 1999 Toyota Sienna P0125
* Ford P0125 P0172 P0175
* P0125 and P1135 OBD Codes on 2000 4 Runner
* P0125 on a 1996 3.8L Mustang
* P0125 in a 2001 Ford Ranger
* p0125 on a ford escort
* I got P0125 Code! 2001 Ford F150
* P0125? Can anyone help me get rid of this code!
* P0125 Insufficient Coolant Temperature for Closed Loop Fuel

Need more help?

If you still need help regarding this trouble code, please post your concern in the forums.

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thomas1

Read this thread carefully, your AF sensors may be bad,
https://www.clublexus.com/forums/sho...t=P0125&page=2

LadyRX300

Thank you for helping me out lexus114, I reset the code but It came up again.. and today when I started the car it was shacking kind of hard. is there a part I can replace to fix this problem, and is it expensive?... (sorry if I'm asking dumb questions, but GIRLS don't know about cars that much.. I have to understand what you are talking about so I can tell my dad, so he can fix it for me)...

lexus114

Show your dad the technical description (post # 4) then we may need to figure out where the temp.sensor is.First have him check the obvious,low coolant level,verify the temp of engine is correct (maybe a bad thermostat)last,maybe bad temperature sensor.

LadyRX300

Do you think the A/F sensor may be bad!... could that be the problem?... or is this code P0125 something totally different from A/F sensor replaced.

Lexmex

I'd have a mechanic check with a more advanced scanner exactly what is being read off of that particular bank. Reason why is that for the RX300 the P0125 code is associated with the A/F sensor itself. It could be something such as the wiring or connection. I would also make sure that the sensor that your father thought is the Denso sensor, not some other aftermarket one.

I can't overemphasize the connection, where the A/F sensor connects to the vehicle itself electronically, it is important to check it has a tight fit and that the contact itself is clean. A mechanic the other day showed me one on a Buick the other day and it was a repeated source of trouble.

mikey00

As Lexmex already said check that sensor and make sure it is a Denso. I am betting that is where the problem lies. If you do a search on the forum on your error code you find more info then you want on P0125 and aftermarket sensors.
Another longshot, check the 25a A/F Heater Fuse inside the fuse box. it supplies power to the sensor heaters.

lexus114

Well their you go LadyRX,I hope our recommendations help you out,keep us posted.

LadyRX300

I got the sensor from Oxygensensors.com I wanted to buy the Denso but they didn't have any... so the guy from oxygensensors.com told me that
Walker sensors are the same thing.. so I order one of those... Part #: 250-54001

Lexmex

Walker makes some fine products, especially their catalytic converters. I knew guys back in Mexico who used their cats for performance (though I went with a Magnaflow), but as far as oxygen sensors and the RX300, it's been hard to use anything but a Denso in the RX300. Unfortunately, I'd have to say you need to replace it with the real Denso part.

LadyRX300

Do you think if I call Oxygensensors.com and tell them that I'm having problems with the sensor they sent me they would replace it.. I'm not trying to pay all that money all over again?...

Lexmex

You can certainly try, but I make no guesses on what they might tell you.