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EML Fault - Air Fuel Sensor 1 (Bank 2)

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Hey all,

 

So I recently went from Berk decats to Motordyne ART pipes as a neighbour was whinging about volume.  This sorted out the whinging fault, but I now appear to be getting the engine management light trip for air fuel sensor 1 (bank 2) which I think is the sensor after the exhaust manifold/header but forward of the cat / decat on the passenger side.  It has been reset and tripped out again.  Any thoughts on what might be causing this?  The code next to the fault says P2A03 on the screenshot from the diagnostics computer.

 

Garage did a pressure test by creating backpressure in exhaust and feeling for leaks but couldn't find anything.

 

Any help would be very much appreciated, seems weird that it was fine, then literally changing from one decat to another is causing just one side to trip.

 

If it makes any difference this has been re-mapped by Horsham Developments, so sensors rear of the decats are disabled.

 

Many thanks in advance for any light you may be able to shed on the matter!

 

Luke =)

Edited by Doom
Clarity

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Hey, thanks for the response.  Would an intake leak not be picked up by a sensor around that part of the engine rather than a sensor after the exhaust manifold?  Actually I've just realised that I have put manifold rather than exhaust manifold on original post which would have led to some confusion, editing now!

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After the TB, there is no sensor the next inline are the upper exhaust sensors that will monitor the lean mix (caused by a vac leak) and dump fuel to compensate/save itself. Has you mpg got worst on a run? 

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When I had a P2AO3 error code it was the exhaust gaskets. Where the manifold and cats meet up. Replaced mine and error code remained off - had to wipe it via OBD. 

 

I own a Z34 not a Z33 though. 

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23 minutes ago, davey_83 said:

After the TB, there is no sensor the next inline are the upper exhaust sensors that will monitor the lean mix (caused by a vac leak) and dump fuel to compensate/save itself. Has you mpg got worst on a run? 

Ah thanks for dropping knowledge!  My average mpg is still hovering at around 22mpg, although that is over time and the fact that I'm not driving it as I normally would due to the EML could be obscuring that.  I will reset the average when I am on the motorway and see if I notice an appreciable difference.  I do get some minor overrun and pops and bangs which I didn't have with the previous decats after the uprev, that could indicate that the ECU is adding more fuel to compensate?

 

23 minutes ago, Umster said:

When I had a P2AO3 error code it was the exhaust gaskets. Where the manifold and cats meet up. Replaced mine and error code remained off - had to wipe it via OBD. 

 

I own a Z34 not a Z33 though. 

The exhaust gaskets are shiny new ones which came with the Motordyne ARTs.  It's sounding a little bit like maybe the passenger side one isn't sitting quite right, although the pressure test didn't turn up anything, and I was poking my hand around that area myself as well as the mechanic to see if I could feel any leaks.  Thanks for the info, seems to be reinforcing a general story here.

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2 minutes ago, Doom said:

The exhaust gaskets are shiny new ones which came with the Motordyne ARTs.  It's sounding a little bit like maybe the passenger side one isn't sitting quite right, although the pressure test didn't turn up anything, and I was poking my hand around that area myself as well as the mechanic to see if I could feel any leaks.  Thanks for the info, seems to be reinforcing a general story here.

Yeah I had Cobra HFC and Cobra CBE and had to swap out the Cobra gaskets as they were terrible. Went back to OEM. 

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Ah ok that's interesting, something for me to look into.  How did you know it was a gasket problem?

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The noise, researching the error code and asking the guys down at @Jez @ H-Dev aka Horsham Developments.

 

Unfortunately I don't have the space/tools to do an exhaust leak check but was pretty sure after listening out for the noise and the background reading. 

 

If you've got axle stands / ramp / non powered car then I'm sure you could get underneath and shine a light at the gaskets. I don't have the picture to hand but mine were blown sideways and it was clear as water that the gaskets were faulty. Hope that helps? 

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Ok, a confusing update to this one!

 

So to test the sensor theory I had the mechanic switch the sensors between banks.  I got the fault again but this time it was on bank one so the other side, which I thought would confirm the theory that it was a sensor.

 

I have purchased and had installed 2 replacement sensors, and a couple of weeks later I have the same issue again, on bank one.

 

Is it possibly pure coincidence that the bank error switched sides when the original sensors swapped sides and actually the fault lies elsewhere?

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I make it one of your original sensors is still good, I would fit that sensor in the location that is now showing as a fault. 

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I would always recommend genuine Nissan Bosch wideband sensors if your car is a UK model.

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Yes its a UK HR. I was told that the Denso sensors would be fine =/ Unfortunately I don't have £500+ to spend on a pair of Bosch O2 sensors given that I'm in the middle of a mortgage application with all of the inherent additional charges that brings =(

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