Hi! New to the forums.

Background: had takeda intake and ark exhaust already installed with tune from rr racing. Had the PPE headers installed but it needed a harness extender.

Bought those from PPE and had them installed. When I started the car, I had two check engine codes p0031 and p0051 which are some broken sensors according to rr racing.

Got the sensors both replaced and now I have a new code. It's p2197 and i looked it up. It says it's my sensors again?? Help!!!

 

I'm sure you've Google'd the codes already, but just in case, the first set of codes, P0031 and P0051, have to do with the heater circuit in the Bank 1 and Bank 2 Air Fuel (A/F) Ratio sensors (Sensor 1 on each Bank).
You replaced both sensors and now have a P2197, which is the sensing circuit for Bank 2 Sensor 1, which should be a new A/F Ratio sensor that you just installed.
So effectively the two new sensors did fix the original codes you had, but now you have a code for a different circuit.
Both the A/F Ratio sensors and the Oxygen sensors in the exhaust have two circuits within them...a heater element circuit (that warms the sensor up) and the sensing circuit (that measures the amount of oxygen in the exhaust).
You have to make sure the correct sensor is installed in the correct location, cause they look almost identical to the naked eye...but the A/F Ratio sensor works on 0-5V scale and the Oxygen sensor works on a 0-1V scale.

So possibilities:

1. The new sensor in Bank 2 Sensor 1 position if faulty (or the wrong sensor)
2. The extension harness from PPE for the Bank 2 Sensor 1 sensor is faulty

Because the PPE harness is between the sensor and vehicle harness, it's now an additional component that could be the problem in an otherwise simple circuit.
I'd start by confirming the part numbers of the two new sensors that were installed to make sure they are correct...it could be as simple as an Oxygen sensor that was installed where it should be an A/F Ratio sensor.

 

I had a replacement harness shipped to me and it didn't seem to do the trick.

It just makes me confused because the sensor I purchased is oem denso and it's brand new.

I've been told it could be an intake leak or a leak by the sensor.

How do I check that?

 

Do you know the part number of the sensor that was installed? I'm sure it's correct, never hurts to double check though.

You could likely rule out an intake leak since the leak would have to be around the manifold, which I assume was not removed when you did the headers.
An exhaust leak would be more likely...perhaps the cylinder head to manifold gasket, or where the A/F sensor threads in, or even at the downpipe flange if it was close enough to the header.

You could try listening for an exhaust leak when the vehicle is cold.
Other than that a smoke machine would be another way to find an exhaust leak.

Assuming the replacement harness was good, then double checking the A/F sensor part number would be next.
If the A/F sensors are the same left and right, then I would swap them. If the code moves to the other Bank, then the sensor is faulty.
If the code stays on the same Bank, then look for an exhaust leak.

 

Would you be able to check my sensor part numbers haha second pair of eyes wouldn't hurt.

 

Here are the part numbers directly from the Denso USA site...I'm assuming you have a RWD IS350:

The numbers above may be found directly on the box the sensor came in.
After some cross checking it would appear these are the correct sensors.
Even though the part numbers are different, the reality is the sensors are the same. Why is the part number different then? Due to where the harness connector location is, the length of the wires from the sensor to the connector will be different. You will note above that the passenger side sensor is the same whether you have AWD or RWD. The Driver's side is different, as that's the side the transfer cause is located for the AWD system, hence the vehicle harness will be routed differently, requiring the sensor to have a different length for the wires.

The step I recommended above about swapping the sensors side to side could still be utilized once there is enough length of wire for the sensors to reach the harness connector...then operation of the sensors are exactly the same.

I've attached the diagnostic steps for P2197. It's more so to give you an idea of what is happening that is triggering the code.

 

I have an AWD. Would it make any difference?

Also, is it safe to drive if I keep clearing the code when it appears? Or should I make this a priority to fix?

Would bringing it to the lexus dealer be the best bet? Even though I have an aftermarket exhaust, headers and intake?

 

I have an AWD. Would it make any difference? No. The sensor head and connector orientation are the same for all the sensors listed above...the length of the wire is the only difference. Where did you get those part numbers from? And do you have the Denso boxes the sensors came in?

Also, is it safe to drive if I keep clearing the code when it appears? Yes and no. When the code is cleared the ECU adjusts fuel trim according to the sensor reading, as the sensor continuously keeps reading lean, it will keep adding fuel to that Bank until it can't then trigger the code. Once the code is triggered, the computer stops trying to correct fuel trim and uses a fixed predetermined value. So it's not the best thing for the car and cats, but it's not going to die tomorrow either.

Or should I make this a priority to fix? Definitely a priority to fix. While the problem exists it's going to cost you more at the fuel pump when you fill up and shorten the life of whatever cats you have on the car.

Would bringing it to the lexus dealer be the best bet? First thing they will want to do is put the car back to stock and diagnose the problem since they don't know if the aftermarket parts is causing the issue. If they put the car back to stock and the issue is solved, that still doesn't leave you with a solution as to what is causing the issue, other than it's one of the aftermarket parts, which is pretty much the point you're at now.

 

I got them online from parts geek. I only have one of the boxes. I threw away the other one.

Where can I bring it to get it checked other than the dealership? I've tried everything except the potential leak from somewhere and I've run out of ideas.

 

The box you have should have one of the Denso part numbers on it...234-9140 or 9143.

Other than the dealer a local performance shop would be your best bet. If they install headers and exhaust systems, this is likely a scenario they've run into before and know how to diagnose/fix it.
If I had to take a complete shot in the dark as to what the issue is, I would guess it's the gasket between the cylinder head and the header...but that's a completely blind guess.

If you had a leak in the intake manifold, then you would have other codes and the engine would run poorly.
If you had a large leak in the exhaust system near the engine, then you would hear it. I suspect the issue is a very small leak that you can't necessarily hear.
If the new sensor was defective, then swapping them side to side would answer the question...maybe the sensor got beat up in the mail.