My SEL illuminated with code of P2A00 (Air Fuel Ratio Sensor Circuit Range/Performance Bank 1 Sensor 1). I ordered a BENSO sensor and I replaced the sensor on the passenger side in the exhaust manifold. Everything went fine until I turned the car back on, my SEL is still illuminated with new codes of P0031 (Air Fuel Ratio Sensor 1 Heater Bank 1 Control Circuit Low) AND P1148 (Closed Loop Control Function Bank 1).

I have tried cleaning and greasing both connectors several times. I even tried plugging in the old sensor (just the electrical connection not in the manifold) and received the same codes. I have also tried resetting the ECU per the instructions and I was successful but SEL illuminated as I was backing out of driveway. What has happened? Is it a bad sensor? Any help much appreciated.

p1148
p0031
p2a00

 

Anyone have any ideas?

 

I had p0031 and p1148 for the O2 sensor. When I replaced the bad sensor with a used OEM one, the codes went away. That was over 20k miles ago. Are you sure you replaced the correct sensor? There are 2 on each side.

 

The code I had was Bank 1 Sensor 1. I replaced the first sensor in the exhaust, in the manifold, on the passenger side.

 

I wish someone could share some results for this. Ive been chasing the same problem for a couple months now.

 

I have replaced both upstream sensors with brand new Denso sensors. I am still getting p0031 p0051 p1148 and p1168.

p0031 - air fuel sensor 1 bank 1 circuit low
p0051 - air fuel sensor 1 bank 2 circuit low
p1148 - closed loop control function bank 1
p1168 - closed loop control function bank 2

What is the problem? What steps can I take next?

 

I am trying to follow the steps outlined on page 159 of the attached PDF, but I am not familiar enough with the electrical diagnosis and locations. I have a multimeter and was able to test the sensors but I feel like I need to test the connectors from the harness to the sensor for voltage but not sure how to go about it.

http://www.nicoclub.com/FSM/G37/Sedan/2009/EC.pdf

 

I think you are over your head?


If it were mine I'd let the dealer do the troubleshooting.

Telcoman

 

If the exhaust or CAT is cracked or sucking air it will throw these codes as well. Infiniti had to replace one of my CAT's cause it cracked. Fixed my issue. The had already tried o2 sensor.

 

I might be reviving an old thread but I was never able to fix the original problem. Check engine light is still on and now its time for tag renewal, unfortunately impossible to do with a CEL. Pull codes and came up with this awesome list:
P1148 Bank 1
P1168 Bank 2
P0037 Bank 1 Sen 2
P0057 Bank 2 Sen 2
P0031 Bank 1 Sen 1
P0051 Bank 2 Sen 1
P0150 o2 circuit Bank 2 Sen 1

What is all of this pointing at, even a guess is appreciated. My scanner can't pull Live Data which may help. Only thing I can think of is wiring harness or faulty cats, any opinions?

 

Do you have any intake or exhaust modifications? Have you reset the ECU after replacing the sensors?

 

Zero mods. I performed a reset, the gas pedal ignition combination. I believe it was for the ECU, it turns the CEL off for about 15-20 seconds but illuminates when you start driving.

 

It certainly seems to be emissions related. I've never heard of cats throwing that many codes on both banks. Have you thoroughly checked the entire exhaust system? How does it run/idle? It may be time to get some professional help.

 

The car runs fine, great actually. The only thing I can hear is at a stop light when the car idles, it idles real low almost to a stall then picks up the rpm. It only does it once a stop, never repeats itself on the same stop.

The only thing I was thinking I could do would be to find a scanner that can check the live data on the vehicle and check all of the readings. All of this was happening after replacing the 02 sensors. I am trying to keep expenses as low as possible and $105/hr for diag around here is too much. We had it at a indy shop but they did more damage and misdiagnosed.

 

Maybe you'll get lucky and someone on the forum who knows WTF they're talking about will chime in. Unfortunately I'm not that guy in this situation. $105 is a lot of money, but you may end up with no choice but to pay it.