P0137 Code O2 Sensor Location? Video included

Just failed my emission test. Getting a P0137 O2 Sensor Circuit Low Voltage Bank 1 Sensor 2 on the OBDII and a check engine light. 2006 Hyundai Sonata 3.3 V6

Can someone tell me where in this video the sensor is located? Bank 1 shows it is passenger side. I do not see any wire or sensor?

The below image location was for a Hyundai Entourage 2007-2008 but says it is for 2006-2008 Sonatas also (did not mention 2.4 or 3.3 though) Anyone know where that image is located in the video?

Would either of these sensors be the O2 sensor bank 1 Sensor 2?

Denso 234-4855 Down-stream sensor (located after catalytic converter) O.E. type " RIGHT " Narrow-Band


Denso 234-4855 Down-stream sensor (located after catalytic converter) O.E. type " LEFT " Narrow-Band


I don’t know where it is located on your vehicle, but “sensor 2” means it is a sensor downstream of the cat. Sensor 1 is the sensor before the cat, usually sensor 1 is near the exhaust manifold. So look for a sensor with wires connected to it on an exhaust pipe downstream of the cat, or on the cat itself. You may have to remove heat shield(s) in various places to locate it. Be sure you are looking on the correct bank, if your car sports more than one cat.

And remember there’s often something that looks like a cat in the exhaust system – the resonator – but that part isn’t the cat.


The primary catalytic converters are built into the exhaust manifolds. Open the hood and look around, you may see the oxygen sensors.


Denso 234-4854 says Downstream Left
Denso 234-4855 says Downstream Right

So there should be two sensors after the cat converter? One on the right side and one on the left side? Right side would be passenger side?

Yes, right side is the passenger side. Usually if there are two downstream sensors, that means there are two cats. One downstream sensor for each cat. From what I see on your car both are heated, using the zirconium/alumina chemistry on both upstream and downstream sensors. A/F rich signal is closer to 1 volt, lean is closer to 0 V. The tip must be hotter than 700 deg F to work, that’s the reason for the heater. The heater coil resistance is appx 10 ohms.

From what I’m seeing your engine has a cat on each bank, possibly incorporated into the exhaust manifold, hard to tell from the diagrams I’m looking at. In any event you have bank one sensor’s 1 and 2, and bank two, sensors 1 and 2 to deal with. 4 total. They’re not all the same part number though. The Bank 1 sensor 2 location is shown the same as the photo you posted above. Are you able to find that sensor? You’re engine is transversely mounted right? If so, bank 2 appears to be closest to the front of the car; implying bank 1 is the side closest to the firewall. So look on the firewall side probably well under the car, you should see the exhaust manifold, then the cat, then after that look for bank 1 sensor 2. It’s possible it fell or broke off, in which case you’ll have to look for the bung-hole where it screws in.

The oem part number for sensor 1 on both banks appears to be: 392103C100
Sensor 2 on the right side : 392103C200
Sensor 2 on the left side: 392103C400

Sorry, don’t know which side is bank 1 and bank 2, right/left or left/right.

It’s possible I’m confused about the meaning of right/left vs front/back, so compare the appearance of the new sensor to the old one to make sure you’ve got the right replacement.

P0137 diagnostics

Code set when output level is below 50 mv (lean) in closed loop for more than 13 seconds over two driving cycles. You may need a Hyundai scan tool to do a complete diagnosis, b/c you need to be able to see the waveforms from the upsteam and downstream sensors simultaneously to know for sure what the problem is. Suggest when you find the sensor to check the heater coil resistance and the robustness of the electrical connection to the sensor first. If rtv silicone sealant has been used in prior repairs, like to seal gaskets in the intnake manifold or exhaust manifold area, that can cause this problem.

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Update: B1S2 on a 2006 Sonata V6 is located just to the left (left if you are sitting in car) of the oil pan underneath the car. Nothing to remove to access it. Just need a 02 socket and maybe some penetrating oil and a propane torch would help. The harness connector is located at the top in the engine compartment on passenger side. To disconnect the harness you have to use a flathead and pry the engine side of the case over that hump at around 5:47 in the video.