Hi all

A few months ago i started to get a repeated ‘emissions system check’ warning that my OBD reader informed me was a P0133 - O2 sensor slow response. For a year or so that had been transient and would clear for a few months. Then it became constant so I figured it was time for new O2 sensor. I initially replaced just the one and then heard it was best to do them in pairs so did both. I bought NTK 22106 sensors and replaced both front sensors even though only back 1 was giving me the P0133 code. I hoped that would fix it but its actually made it worse. I now have P2195 & 2197 ‘stuck lean’ codes on both banks. Checked plugs were in tight and no leaks. Reset computer with code reader but both codes came right back. Tried resetting ECU viola battery pull to check if it was ECU making fuel trims but codes are persistent. Next I swapped the front and rear O2 sensors since the rear pair where the originals and didnt have any issues but codes immediately return - again after ECU reset. The front ones are used for fueling and the back ones for saving polar bears. The codes returned as ‘pending’ within about 1 minute of starting - so presumably the second the sensor gets up to temp and goes closed-loop.

Since I had no issues before I tried to fix the slow O2 sensor I am hesitant to think I have a real fuel issue but I am not ruling that out.

Other than checking the sensors with a volt meter - which I really dont want to do as I have no lift so I will likely burn the crap out of my hands or arms - I can only think of getting 2 more sensors from Motorcraft (the ones recommenced by Astin1936 in his research of OEM sensors being Ford).

The job is super fiddly so its likely I touched the sensitive section of the sensor with dirty gloves. Are they that sensitive? What code would I get if they are dirty?
Anyone have any other ideas?

Thanks

 

it's unclear to me, after reading your post several times, how many NEW sensors you have installed. if all of them are NOT new, i would, first of all, make certain that they were.

 

So, on the DB9 this is kind of tricky... Since you don't say the model/yr of the car I will offer that there are effectively 4 banks for the DB9. Each ECM has "two" banks. IOW, Cylinders 1,2,3 are a bank 1, 4,5,6 are bank 2 for that ECM... The other ECM has the corresponding 2 banks. This means that an error for "Downstream Bank 2" could correspond to one of two sensors - on on the LH side of the engine, and one on the RH side... [Normally, I wouldn't admit to this but this took me multiple tries to figure out... All this because AM uses two 6 cylinder ECM systems to run the V12. I note in passing that the Ferrari Testarossa that I was looking at "Cars and Coffee" uses 2 Bosch 6 Cyl. K-Tronic systems for the same reason - 6 Cylinder systems are cheap and reliable...

Thus, when reading a code you have to know which ECM you are interrogating. My Foxwell lets me set which ECM I'm reading, and I go from there. So you actually have two bank 1, and two bank 2s which leads to 4 downstream sensors, 4 upstream sensors.

With all of that as preamble... What car, and which ECM (side of engine, RH or LH) are you working on?

Best of luck!
Larry

 

I bought 2 sensors and installed both up front; bank 1 before the cat and bank 2 before the cat. Yesterday I swapped them both front to back so both blew sensors are now after the cat. I was hoping that if there was somehow a problem with my new sensors that the error code would change to something less scary than ‘stuck lean’. Sadly it didnt change. That makes me wonder if I have now dirtied all the sensors or if Ive twisted the crap out of the wires.

 

My apologies. You’d think that in all my rambling I would have mentioned what car I am talking about. This is an 2007 V8V so I am only working with 4 possible sensors.

I watched the YouTube video from Aston1936 about the DB9 sensors. I am kinda jealous that on the DB9 they can be accessed without needing to either a) drop the exhaust and heat shield or b) try to run bits of string up above the heat shield and try to pull the wire hardness through a tiny space. Because I chose option b I also had issues with trying to stop the wires getting all twisted when you screw the sensors in. Every rotation of the sensor rotates the wires and its a fine thread. Once the sensor is screwed in the cables cannot be straighten out so they stay badly twisted. I tried twisted the cable in the opposite direction before screwing them in but it didn’t help.

 

Hi @tranceatlantic

I was going to weigh in here before your post #5.

Based on everything you've described so far, and if the O2 sensors are the "correct" P/N to function in this application, then I wanted to suggest a possible cable issue(s).

I've done a lot of O2 sensor replacements over the years and know how much of an effort it can take to keep the harness from twisting, but I always made sure it was unfurled before plugging in the sensor. If yours has no relief, and I do know how many turns it takes to get the sensor seated, I would not be comfortable with it that way.

One trick I've used in the past is to wind up the sensor in the other direction before starting the thread. That way, as you thread the sensor in, the harness is unwinding. Even if it is not perfect, if you get it half or 3/4 wound in the opposite direction it would only have a small twist left in the harness. Now that you have the P2195/97 you might have done some harm to the harness connections on the new units.

Good luck, hope you keep your situation updated. I am curious how this resolves.

Best,

 

Based on the above I think it's highly probable you damaged the sensors during the install... The wiring can take the heat but doesn't like being twisted which pulls the bond from the sensor element. You can test the sensor with a DVM and a blow torch to confirm. Lots of good youtube videos on how to test...

 

Thanks for the advice. I just bought 4 new Motorcraft DY1401 at about $60 each. These are the sensor that apparently Ford supplied to Aston Martin. Per the videos by Aston1936: these are installed on the same age DB9. I am going to try to install them without running the cable over the heat shield - just so I can test that it fixes the issue and rules out wire kinks.
I was wondering if any one has any knowledge of using the Motorcraft DY1401 in the V8V?

 

Here is a quick update. I have been dealing with this ‘stuck lean’ issue for many months, The issue is driving me crazy. I am convinced the car is not actually running lean, but thinks it is due to either faulty sensors (I have replaced every one of the 4 sensors in the V8V - half of them twice, with 6 new sensors, and the fault never changes. I have looked for leaks in the exhaust when air might get in and lead to a lean reading. i cant find anything. I’ve tried blowing smoke in my garage and looking under the car but to no avail. It seems unlikely to be from the sensors themselves because there are so many turns on those threads I dont see how they could leak.
Additionally, the car drives like it runs lean rich, not lean. It smells of unburnt fuel and it bogs down at low RPM, especially just after start up.
I have gotten into to the habit of clearing the ECU before start-up and this makes it run better because it is not trying to drown the engine in fuel.
So given that the brain is trying to correct a lean issue that is not real, what to do? Is there any other common issues that might cause this? It’s there a joint that leaks air into the exhaust that I may have damaged? Is it worth looking at a new ECU? Is there a wiring harness that could be replaced that doesnt require a whole new loom?

 

Have you looked at or replaced the MAF(s)? plural if lean on both sides? The MAF starts the fueling process as it tells the ECU the volume of air coming in then the ECU has to measure the correct amount of fuel. Finally, there is a "test" at the end of the combustion cycle that tells the ECU the fuel was either too much or too little (via the O2 sensor FB). So, if the Volume is incorrect because the MAF is off, then in one instance, the ECU fuels it with less than optimal fuel, the O2 sensors come back with lean. Same thing for the next combustion cycle. It could go the other way with a bad MAF too and less air is entering than the ECU thinks BD the MAF is incorrect.

If the MAFS are good and the O2 sensors keep reporting lean, then the only thing left are fuel injectors.

Finally - is this a factory tune? I've seen tuners (we called them tooners) that really didn't know what they were doing and can create a lot of havoc if you let them in.

 

Is there any update on this? Similar to you, I had a P0133 on bank 1 sensor 1, and after replacing, I'm now reading a P2195 on the same sensor.