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I am receiving these codes on my 99 RX300 with about 89K miles and very poor gas mileage of around 11MPG. This car has been in the family and had not had any major work done. I had an O2 sensor changed about 10 years ago. I have cleaned the MAF sensor but that hasn't changed anything. I have read through many discussions on this forum about these codes including the one here. I would rather not replace 3 sensors if only one needs replacing and am willing to replace all that really need to be replaced. Please help me out in a sequential approach as to which one to change first and next. Attached are a few reports from my ODBC sensor. I also posted quite a few screenshots and reports (post #348) on the thread about bad gas mileage but that being an old thread, didn't get a response.
The only 'maintenance' I have been doing on this car is Oil/Filter change and air filter change regularly and brake rotors/pads. The car has not given me any problems. Are there other maintenance tasks that must be performed at this stage (coolant thermostat change, timing belt, transmission oil change, PCV valve change, ...anything else?) but first I need to fix these codes.
I will buy the parts and have access to a local shop who will do the work. Please advise how should I proceed.
Focus on P1155. Fortunately this A/F sensor is easily accessible on Bank 2 plus you can confirm it has a faulty heater circuit with a VOM (unless you have an issue in the wiring harness or a ECU, which is unlikely). You may have something else going on because a faulty A/F heater will not materially affect mileage or engine performance. Replacing Bank 2 A/F sensor will almost certainly take care of the other two “companion” codes.
I understand there is one A/F sensor on the exhaust manifolds at each of the cylinder banks and one O2 sensor each near Catalytic Converter in this model. What are the part numbers for each?
I understand there is one A/F sensor on the exhaust manifolds at each of the cylinder banks and one O2 sensor each near Catalytic Converter in this model. What are the part numbers for each?
look up on Denso website then buy from Rockauto or amazon
look up on Denso website then buy from Rockauto or amazon
Thank you. I looked at http://densoautoparts.com
They list Air Fuel ratio Sensor: 234-9009. I assume it the same for all four Air Fuel Sensors.
I am prepared to change this sensor but what could be causing Bank 2 Sensor 1 giving the negative values?
Readings at various RPM
Last edited by rmk9785e; 04-08-18 at 10:09 PM.
Reason: Added readings at various RPM
Thank you. I looked at http://densoautoparts.com
They list Air Fuel ratio Sensor: 234-9009. I assume it the same for all four Air Fuel Sensors.
I am prepared to change this sensor but what could be causing Bank 2 Sensor 1 giving the negative values?
Readings at various RPM
To me the above says you are too rich on bank 2.
As you open the throttle wide it leans out.
Would this more likely be an injector issue?
Looks like an injector issue to me too but I would not chase it until I fixed the known A/F sensor issue.
Just to help me understand, which symptoms affirm that there is an issue with the A/F sensor? The Schrodingers Box Fuel Trim videos referenced in this forum encourage learning the troubleshooting process before changing parts. I've viewed the videos a couple of times and am still learning.
Trying to replace the Bank 2 Sensor 1 A/F sensor didn't go as well as planned. The auto shop couldn't remove the sensor while in the car so they removed the manifold and still could not break the rusted seal. Their solution was to take to a welding shop that works on exhausts. That shop cut out the sensor and welded a new piece for installing the sensor. I am concerned that the new contortion doesn't let the sensor tip protrude deep into the path of the exhaust gases. Please see the attached photos. The exhaust shop welder says this is how they do it for many vehicles and it works.
I can't find the Bank 2 exhaust manifold at the local salvage yards and the new one costs about $330 + tax which would not be my first choice. My other options seems to be:
1- Find a salvage yard further out (40+ miles)
2- Use the welded one and hope that it will accurately sense the A/F ratio.
Do you think there is sufficient exposure to exhaust gases for it to work as shown?
Is there a better source for salvaged parts that I can order online? I am told this engine was installed in 99-03 RX300 and 01-03 Highlander 6 Cylinder (1MZFE engine).
Seems like a good weld, but concern is valid. I would have suggested a conversation with the welder before the work was authorized.
If they have been doing this and no return came back to them, then very likely it will work for you too. Well the system may not work perfectly but it would not generate a CEL. The gasses in the small cavity will get the post combustion gases, but they may not be the instantaneous readings you would get if the sensor was in its intended position. Also check wire clearance as the sensor is now going to stick out.
Teh delima is should you assemble as is or get a replacement. If you are not a purist, just have it assembled but get the mechanic to agree that he will not charge labor for redo if the fixed up does not work.
Too late for you but I will post this for others. I also had a Bank 2 A/F sensor that was too rusted to remove. Had to remove manifold to improve access. It took a little effort but it was fairly straightforward to make a couple axial cuts and chisel put sensor, very similar to how you would remove a frozen wheel bearing race. Once removed, you can chase threads and be back in business. There was no reason to butcher your manifold the way they.
04-04-18, 02:56 PM
P0125, P1155 and possible P0171
