Need some assistance from Electrical Gurus
06-01-14, 09:21 PM
#1
Need some assistance from Electrical Gurus
I got two CEL codes the other day.
#1: P0125: Coolant Temp/Closed Loop
#2: P1155: Heater Circuit Bank 2 Sensor 1
I read a few threads about P0125 and it seems like it always shows up with an Air/Fuel sensor code. Basically there is an electrical problem with the sensor/wiring. A lack of response from the sensor will trigger the P0125.
I hooked up my laptop scanner to monitor live data and noticed that B2S1 was unresponsive to throttle inputs in Closed Loop, while B1S1 was very quick to jump up and down.
I replaced B1S1 with a Denso sensor about a year ago, maybe more. The B2S1 sensor is the original Lexus sensor from B1S1 (I switched them around). So what I'm saying is that I'm 90% certain that the sensor is dead, but I would like to make sure it's not an input and/or wiring problem.
Is there an Ohm test I can do on the sensor to check its integrity?
p.s.: Freeze Frame data shows that my Long Term Fuel Trim on Bank 2 was at almost 17% when the CEL came on!
#1: P0125: Coolant Temp/Closed Loop
#2: P1155: Heater Circuit Bank 2 Sensor 1
I read a few threads about P0125 and it seems like it always shows up with an Air/Fuel sensor code. Basically there is an electrical problem with the sensor/wiring. A lack of response from the sensor will trigger the P0125.
I hooked up my laptop scanner to monitor live data and noticed that B2S1 was unresponsive to throttle inputs in Closed Loop, while B1S1 was very quick to jump up and down.
I replaced B1S1 with a Denso sensor about a year ago, maybe more. The B2S1 sensor is the original Lexus sensor from B1S1 (I switched them around). So what I'm saying is that I'm 90% certain that the sensor is dead, but I would like to make sure it's not an input and/or wiring problem.
Is there an Ohm test I can do on the sensor to check its integrity?
p.s.: Freeze Frame data shows that my Long Term Fuel Trim on Bank 2 was at almost 17% when the CEL came on!
06-01-14, 10:11 PM
#2
You're correct in saying that P0125 typically comes with a AFS code. While you're probably right about the sensor being dead, its always best to check before replacing. While the engine is cold the resistance of the sensor should be 0.8-1.4 ohms
06-01-14, 10:13 PM
#3
I apologize, I posted AFS for a california vehicle. You're probably not a california spec car... heated oxygen sensors on a cold engine should be between 11-16 ohms. Sorry for the mix up.
06-02-14, 06:28 AM
#5
Lexus Test Driver
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06-16-14, 09:00 PM
#8
Just wanted to give an update and thank the people who helped me out.
I did a resistance check on the original sensor and realized that the circuit was open, possibly due to broken wires/heating element. The new sensor was right in the good range, around 1.1 Ohms. So this made me feel that much more confident about swapping the sensor.
The replacement took about 10 minutes. I cleared the code, made two trips since then and have not seen the CEL come back. Woohoo!
p.s.: I used a Denso Air/Fuel Sensor for California Spec cars, part number 234-9009. It's good for both banks (B2S1 and B1S1).
I did a resistance check on the original sensor and realized that the circuit was open, possibly due to broken wires/heating element. The new sensor was right in the good range, around 1.1 Ohms. So this made me feel that much more confident about swapping the sensor.
The replacement took about 10 minutes. I cleared the code, made two trips since then and have not seen the CEL come back. Woohoo!
p.s.: I used a Denso Air/Fuel Sensor for California Spec cars, part number 234-9009. It's good for both banks (B2S1 and B1S1).
Last edited by Hayk; 06-16-14 at 09:06 PM.
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