Check engine light o2 sensor 05 Tacoma

Hi all. So I got my truck inspected the other day in NYS. Wouldn't ya know it, an hour after I got my sticker, the check engine light came on. It never has before. Glad it happened AFTER, or I would have failed. I've got a 2005 Tacoma, 4 cyl. I pulled the codes with a cheap scanner, and cleared them, but the light came back on, so something is up. The code I got is a P0137. Oxygen sensor, Bank 1 sensor 2, low voltage it says. After some research, and youtube watching, it seems to be the heated o2 sensor right after the catalytic converter. I ordered a new one from the parts store. Autozone, Advance Auto, and Rock auto all had several selections for the sensor. I ordered the

$48 Denso 234-4261 Oxygen Sensor with 4-Wire 10” Harness for Lexus/Toyota V-6 Downstream Left/Front

Denso 234-4261. I ordered it because it said the Denso one was the OEM sensor on Autozone's website, vs the other choices that just said "exact fit aftermarket part". Can anyone verify this is correct? I don't really trust Autozone as a source of factory parts information. I really need to get a factory service manual.

The sensor should be here soon. I have had REALLY bad luck replacing o2 sensors in the past on other vehicles. It seems like I always need to order 2, just to get 1 good one. Anyone else have this problem? Same with parts store TPS sensors. Hopefully this isn't the case this time.

Can anything else cause this code? Other than an exhaust leak, or maybe a bad catalytic converter?

Anyone have experiences to share?

Thanks,
Matt

 

I had the equivalent code for my rear 02 sensor on my 04 and replacing the sensor solved it

 

Always stick with Denso or NTK for 02 sensors.

 

Soooo......I put the new sensor in today, and checked for exhaust leaks up front. No leaks. Cleared codes, took it for a drive, and engine light is back on..... Same code. Any ideas?

 

Service Manual: http://www.customtacos.com/tech.old/files/05FSM/repair.html

For the 4 cylinder P0137 Code: https://www.customtacos.com/tech.ol...06toyrm/06toypdf/06rmsrc/rm2006ta/0060026.pdf

Triggers:

• Low voltage (open):
During active air-fuel ratio control, following conditions (a) and (b) met for certain period of time (1 trip detection logic):
(a) HO2 sensor voltage output less than 0.21 V
(b) Target air-fuel ratio rich

• High impedance:
Sensor impedance 15 kΩ or more for more than 90 seconds when ECM presumes sensor to being warmed up and operating normally (1 trip detection logic)

Causes:

•Open in HO2 sensor (sensor 2) circuit
• HO2 sensor (sensor 2)
•HO2 sensor (sensor 2) heater
•EFI relay
•Gas leakage from exhaust system

 

Thanks! The manual is always helpful. I'm leaning toward an open in the circuit....perhaps a bad wire in the harness. I'll have to do some more poking around. The frame was recently replaced, so a wire could conceivably have gotten stretched/kinked/pinched.....

 

I agree. Go through the wire harness.