Hello my RX300 99 is throwing code p1130 (bank 1 sensor 1) and sometimes p0125 that seems related to the A/F sensor code.
I already replaced the A/F sensor with a denso one (bought at rockauto), in fact i replaced both (bank 1 and bank 2) and code still persists.
is there anything else besides the A/F sensor that triggers that code?

 

hello please help me with your comments. thank you

 

I don't have the path/link handy, but search the net for a white board explanation [it is generic ... not limited to RX first gen].

You would need an OBDII reader with live data and then with the understanding of the above mentioned explanation, you will be able to diagnose.

Keep in mind the system is closed loop [oxygen coming in to unburnt fuel leaving]. One way to diagnose is to open loop the system [needs know how] and the other will be to read the live data and determine what is going on.

Salim

 

Hey Salim, maybe you can answer this. I'm assuming you have the diagnostics manual. P0125 is on page DI-42, and is described as "Insufficient Coolant Temp. for Closed Loop Fuel Control". Page DI-42 says the trouble areas are:

• Fuel system
• Injector
• Ignition system
• Gas leakage on exhaust system
• Open or short in A/F sensor circuit (bank 1, 2 sensor 1)
• A/F sensors (bank 1, 2 sensor 1)
• Engine ECU

Page DI-14 summarizes P0125 but the trouble areas are not identical. That page says:

• Air induction system
• Fuel pressure
• Injector injection
• Gas leakage on exhaust system
• Open or short in heated oxygen sensor (bank 1 sensor 1) circuit
• Oxygen sensor (bank 1 sensor 1)

So the list of trouble areas doesn't match, and there is nothing coolant temperature related in either list.
Is the diagnostic manual wrong? I thought P0125 was meant to indicate that the coolant temperature was lower than it should be for proper A/F sensor operation.

 

The question is well beyond my abilities to answer.

Incidentally, I thought you posted the link to the white-board explanation couple of months back. Pardon me if I am wrong.

Salim

 

I think that was for fuel trims.
Your suggestion is probably the right course - look at the live and freeze-frame data.

 

ok so i checked live data on my obd2 scanner and this is what i found:
A/F sensors voltage: 0.7V (both)
Fuel trim bank 1 (cold start): 19.5%
Fuel trim bank 2 (cold start): -13.3%
Fuel trim bank 1 (operating temp): 0.0%
Fuel trim bank 2 (operating temp): -4.7%
let me know if this tells something or you need more data. thank you

 

What freeze-frame data was recorded when it threw the P1130?

 

No code yet but i can tell you that once it reaches op temperature, fuel trim bank 1 stays frozen at 0.0%, i guess thats not normal

 

Short term trim should move to zero as long term trim adapts.
If you want to understand trim see https://www.clublexus.com/forums/rx-...l#post11135160