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My 2010 SC430 (133,000 miles) has the CEL light on, the VSC light flashing and the anti-skid light on. These lights typically come on each time the car is started and stay on the entire time the car is running, but inexplicable sometimes don't come on and stay off for days or maybe a week. I estimate that over 90% of the time the car is started, they come on and remain on. It is throwing P0420, P0136 and P0137 codes for bank 1, sensor 2.
I have three (simple?) questions:
(1) is the Bank 1 sensor 2, the right side downstream oxygen sensor? (I have conflicting info on whether it is right side or left side.)
(2) the P0137 code says "Oxygen Sensor Circuit Low Voltage (Bank 1 Sensor 2)" Does this suggest/mean the problem is the sensor's electrical connection is defective, as opposed to the sensor itself? The car is not exhibiting any other electrical issues.
(3) is the electronic connection for the bank 1 sensor 2 cable located inside the car, under the side carpet on the passenger's side? There is a YouTube vid showing that location, but that vid is for a 1st gen SC430. I am essentially asking if that location changed for 2nd gen SC430's. If the location hasn't changed, it means either cutting the carpet (the vid's suggestion) or removing enough "stuff" to lift up the carpet to access the connection.
My 2010 SC430 (133,000 miles) has the CEL light on, the VSC light flashing and the anti-skid light on. These lights typically come on each time the car is started and stay on the entire time the car is running, but inexplicable sometimes don't come on and stay off for days or maybe a week. I estimate that over 90% of the time the car is started, they come on and remain on. It is throwing P0420, P0136 and P0137 codes for bank 1, sensor 2.
I have three (simple?) questions:
(1) is the Bank 1 sensor 2, the right side downstream oxygen sensor? (I have conflicting info on whether it is right side or left side.)
(2) the P0137 code says "Oxygen Sensor Circuit Low Voltage (Bank 1 Sensor 2)" Does this suggest/mean the problem is the sensor's electrical connection is defective, as opposed to the sensor itself? The car is not exhibiting any other electrical issues.
(3) is the electronic connection for the bank 1 sensor 2 cable located inside the car, under the side carpet on the passenger's side? There is a YouTube vid showing that location, but that vid is for a 1st gen SC430. I am essentially asking if that location changed for 2nd gen SC430's. If the location hasn't changed, it means either cutting the carpet (the vid's suggestion) or removing enough "stuff" to lift up the carpet to access the connection.
P0420 is the left or drivers side Catalyst
you probably received the P0420 code because the Drivers side O2 downstream sensor is bad since you also received the P0136 & P0137 codes.
downstream = the O2 sensor past the Catalyst or closer to the tailpipe.
question, did you just take the car out of storage?
if so, you may need to check the wires…rodents like to chew them up.
Agree, the downstream sensor on driver's side. The connector is unfortunately the one under the carpeting. Get the waterproofing grommet done correctly when replacing that sensor.
Thank you for the replies! Very helpful. The car has never been in storage. Its the closest I have to an every day driver; bought it from a relative at ~2 years old and with less than 10,000 miles on it. It's well maintained and in all respects other that this issue, in excellent condition.
I mentioned in my original message that I had conflicting info on which side Bank 1 is. Thought you might be interested to know our Lexus dealership originally diagnosed it as part of a 7 page "multipoint inspection". The dealership's report says "Replace bank 1 Cat. (found code P0420 Bank MI Cat efficiency)". The service manager that I met with at the time wrote on that report immediately following those quoted words: "Right hands side or passenger"; saying Bank 1 is right hand side. Moreover, I obtained a 10-page Solera Indentifix Report that has a diagram of the exhaust system from the manifold to the tail pipe assembly that labels the right side as Bank 1. It also shows upstream and downstream sensors, etc. Happy to send a pic of those if you like.
Thank you for the replies! Very helpful. The car has never been in storage. Its the closest I have to an every day driver; bought it from a relative at ~2 years old and with less than 10,000 miles on it. It's well maintained and in all respects other that this issue, in excellent condition.
I mentioned in my original message that I had conflicting info on which side Bank 1 is. Thought you might be interested to know our Lexus dealership originally diagnosed it as part of a 7 page "multipoint inspection". The dealership's report says "Replace bank 1 Cat. (found code P0420 Bank MI Cat efficiency)". The service manager that I met with at the time wrote on that report immediately following those quoted words: "Right hands side or passenger"; saying Bank 1 is right hand side. Moreover, I obtained a 10-page Solera Indentifix Report that has a diagram of the exhaust system from the manifold to the tail pipe assembly that labels the right side as Bank 1. It also shows upstream and downstream sensors, etc. Happy to send a pic of those if you like.
a Solara is a transverse V6 engine or an I4 engine, not rear wheel, the V6 bank 1 is on the radiator side and bank 2 is on the firewall side…
Seattle SCone - Thx you for the diagram; very clear!
Bgw70 - Actually, I was not referring to a Solera automobile, but rather to an exhaust system report on my SC430 from Solera Identifix. Solera Identifix is a company that provides software for diagnosis and auto repair to subscribing auto repair shops and DYIs. https://www.solera.com/solutions/veh...air/identifix/
Here is a copy of a diagram from that 10-page Solera Identifix report that I now believe INCORRECTLY identifies Bank 1 & 2:
Raven01750 - I am a recent born-again DIY guy ... monumentally less sophisticated than those on this site! Regarding replacing the sensors on the SC430, my preliminary conclusion is that the toughest part is the electrical connection end, as it is so inconveniently located in the car, and essentially under the console. I am considering installing a spark plug nonfouler on the end that screws into the exhaust and stopping with that. From your experience, do you think there is enough "play" in the wire to unscrew the sensor without disconnecting the electrical end?
The problem isn't unscrewing it because since it's a part that you don't care about. It's getting the new part back in without having the wire all twisted up when it is installed. I did it the right way myself. I took the time to remove the center console. But I'll admit, I thought seriously about just cutting the old sensor and splicing in the new one without having to disturb the rubber gasket through the floorboard.
I'll tell you something else. If I had to go through all the trouble of removing the center console, I was going to change BOTH sensors. Both Bank 1 and 2. I do that because these parts are already older. One goes, the other MAY be not far behind.
Lastly the thing that I say often, is a code is nothing more than a symptom. Until you find out if the part failed due to it just wearing out, or maybe someone previously used a chemical that destroyed it, or it is contaminated with oil replacing the sensor may or may not be the final repair.
We all started as new DIY'ers. If you want to own an older car this it is basically a necessity and I applaud you for taking the time, effort and commitment to really truely make the experience of owning this car even more rewarding than just driving it. 😁👍
I'm good at splicing wires and protecting them with shrink tubing and sealant, so I would likely go this route if/when my #2 sensors fail. Too, then I wouldn't feel the need to replace both. I've replaced a single sensor in a four-sensor system and never had to go back and replace any of the other three over the life of the vehicle.
Seattle SCone - Thx you for the diagram; very clear!
Bgw70 - Actually, I was not referring to a Solera automobile, but rather to an exhaust system report on my SC430 from Solera Identifix. Solera Identifix is a company that provides software for diagnosis and auto repair to subscribing auto repair shops and DYIs. https://www.solera.com/solutions/veh...air/identifix/
Here is a copy of a diagram from that 10-page Solera Identifix report that I now believe INCORRECTLY identifies Bank 1 & 2:
i totally misunderstood…thanks for setting me straight. The diagram does have the Banks backwards…another way to know is Bank1 is always on the same side as cylinder 1.
Please be sure to let us know everything turns out.
Before I put in the non fouler, I would buy the sensor and splice it in. If you take the old O2 sensor out of the stream, your car's ECU is not going to know how to tune your engine and you will end up either running rich or running lean.
Raven01750 - The problem isn't unscrewing it because since it's a part that you don't care about. It's getting the new part back in without having the wire all twisted up when it is installed.
DshngDaryl - If you take the old O2 sensor out of the stream, your car's ECU is not going to know how to tune your engine and you will end up either running rich or running lean.
My last post may have caused some confusion. The non-fouler installation procedure would be: (1) the wire leading from the Bank 1 downstream sensor 2 to the interior of the car would be disconnected from the clips attaching and stablizing that wire as it leads to the interior, but the electrical end of the wire would not be not be disconnected (to avoid all the work of taking the console and carpet out, etc.) (2) the Bank1 downstream sensor 2 would then be unscrewed from the exhaust, (3) the non-fouler would be screwed into the exhaust where the sensor 2 was removed, (4) and then that sensor 2 would be screwed into the non-fouler. The non-fouler is effectively a spacer. The original sensor 2 remains a part we care about because it will continue to be used, and will not be replaced by a new one.
The question I was trying to pose is: do you think it is possible to unscrew the sensor 2 while the other end is still connected inside the car? Bear in mind the threads on the sensor are only about 5/16 inch long, and the wire is ~12.5" long ... it takes 2.25 turns to screw the sensor into the non-fouler finger-tight, plus the additional partial turn to compress the washer.
DashngDaryl - Even though the sensor 2 will be back in place, albeit through a spacer (non-fouler), do you think this procedure will cause the car's ECU to not know how to tune the engine? FYI, I am fearful that you are correct, i.e. that this procedure will interfere with the car's ECU.
Photos of non-fouler below. The sensor 2 in photos below would not be installed; it is only used to verify that the threads match.
05-11-23, 08:49 AM
Bank 1 sensor 2
