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I HAVE A 1999 LEXUS RX300 and the check engine light just came on. I recently had the transfer case (transmission) replaced and the check engine light came on after the work was completed. the transmission shop checked the "check engine" light out and detected something about a "closed loop" from the diagnosis. they reset the light but it came back on. I took it to a repair shop where they ran a diagnostic and determined that the engine was not getting warm enough and replaced the thermastat. That didn't fix the problem either. what other issues could be causing the "check engine" light to come on? It doesn't blink when it comes on, it just comes on after the car has been driven a few minutes.

Optional Information:
1999 Lexus RX 300 3.0

Already Tried:
REPLACED THERMASTAT

Submitted: 1391 days and 19 hours ago.

Category: Car

Value: $25

Status: AWAITING CUSTOMER ACTION

Posted by autodoc_2000 1391 days and 18 hours ago.

Answer

Do you remember what the codes is? If not you can go to AutoZone and they will check codes for you at no charge. It is nearly impossible to diagnose without knowing what the code number is. Once you have the code let me know and I will try to help you from there.

1391 days and 10 hours ago.

Reply

I will get autozone to analyze and will get back to you with code.
Thanks

1390 days and 20 hours ago.

Reply

the codes that autozone came back with are:

P0125: the PCM has determined that the amount of time it took for the coolant temperature sensor to reach an imput value consistent with closed loop operation was excessive.

P1135: pedal position sensor A circuit intermittent.

please interpret these codes and let me know what parts/sensors I need to replace.

Posted by autodoc_2000 1390 days and 18 hours ago.

Answer

Are you sure of the definitions of the codes. The repair information I have says that P0125 is for the oxygen sensor before catalytic converter.

P1135 is for the oxygen sensor heater in the after converter oxygen sensor.

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1390 days and 16 hours ago.

Reply

Of all the information that I have found online. There are two A/F ratio sensors on this vehicle and one o2 sensor (after cat. conv.) one on each exhaust manifold and one after cat. conv. For a total of 3 "O2" sensors. Most of the info. that I've gathered seems to be pointing toward the A/F ratio sensor that is nearest the firewall before the cat. convert.(bank1 sensor1). From the info. I've gathered-and correct me if I'm wrong- Bank1 sensor1 is coming off rear manifold (near firewall) before cat. convert. Bank1 Sensor2 is the o2 sensor located after the cat. conv. before the muffler. Bank2 sensor1 is the one on the front manifold (easiest to access under hood). Nothing I've read leads me to believe the sensor after the cat. conv. is bad. Please elabortate on what you think the problem may be and why. Thanks

Edited by XXXXXXX on 2/2/2006 at 5:34 PM

Posted by autodoc_2000 1389 days and 23 hours ago.

Answer

You are correct I misread the info, but posted the correct info. The codes are for the precat oxygen sensors. Do you want diagnostic information or do you just want to know what componants the codes refer to?

1389 days and 19 hours ago.

Reply

What componants do I need to replace?

Posted by autodoc_2000 1389 days and 19 hours ago.

Answer

If you are replacing parts I would start with the two oxygen sensors between the catalytic converter and the engine. You may replace them and still have a problem though. Without knowing for sure if the wires or the computer are ok. Oxygen sensors are one of those items that should be replaced periodically. They used to say 60,000 miles, but now I think it is around 100,000.

1389 days and 18 hours ago.

Reply

Unfortunately these o2 sensors are $170.00 each!!
It would be more helpful if you could point to the one causing the problem. Otherwise I could spend $500.00+ in parts and replace all three and hope for the best.

Posted by autodoc_2000 1389 days and 18 hours ago.

Answer

The only way to kow for sure is to do the voltage checks and ohm readings on the sensors. Do you have the test equipment to do this?

1389 days and 10 hours ago.

Reply

Reply to autodoc_2000's Post: The other posts I've read online seem to be more specific than the info. you are giving me. I'm affraid that the info. you gave earlier (code:1135-o2 sensor aft. cat. conv. not working) almost led me down the wrong path. My research outside of our converstation(s)has yeilded me better results. The decision I make on this repair will be based on the majority of info I gathered from the website-clublexus.com. I found more specific info. on this site than I found anywhere else.
Thanks for your effort.

Answer

Thanks for my effort. You have not answered th equestions I have asked you. Do you have test equipment that you can test the component and wiring or are you just going to throw parts at it if you have test equipment then I can send you the info needed to find out which sensor it is without the test equipment it is only a guess. I have taken the time to try to help you with your problem and I get a thank you for your effort.

Accepts:
Expert:	autodoc_2000
Pos. Feedback:	98.4 %
Answered:	2/4/2006

Auto Service Technician

ASE Master Tech w/ Advance Engine Performance

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Answer

Do you remember what the codes is? If not you can go to AutoZone and they will check codes for you at no charge. It is nearly impossible to diagnose without knowing what the code number is. Once you have the code let me know and I will try to help you from there.

Reply

I will get autozone to analyze and will get back to you with code. Thanks

Reply

Answer

Are you sure of the definitions of the codes. The repair information I have says that P0125 is for the oxygen sensor before catalytic converter. P1135 is for the oxygen sensor heater in the after converter oxygen sensor. View Full Image View Full Image

Reply

Answer

You are correct I misread the info, but posted the correct info. The codes are for the precat oxygen sensors. Do you want diagnostic information or do you just want to know what componants the codes refer to?

Reply

What componants do I need to replace?

Answer

Reply

Unfortunately these o2 sensors are $170.00 each!! It would be more helpful if you could point to the one causing the problem. Otherwise I could spend $500.00+ in parts and replace all three and hope for the best.

Answer

The only way to kow for sure is to do the voltage checks and ohm readings on the sensors. Do you have the test equipment to do this?

Reply

Answer

Related Car Questions

I will get autozone to analyze and will get back to you with code.
Thanks

Are you sure of the definitions of the codes. The repair information I have says that P0125 is for the oxygen sensor before catalytic converter.

P1135 is for the oxygen sensor heater in the after converter oxygen sensor.

View Full Image

View Full Image

Unfortunately these o2 sensors are $170.00 each!!
It would be more helpful if you could point to the one causing the problem. Otherwise I could spend $500.00+ in parts and replace all three and hope for the best.