Intermittent P0130

[jinjur]

Hi all,

In the past couple of months, I have had the EML and P0130 error thrown in my car, usually at start-up accompanied with a bit of an off smell from the exhaust.

I suspect that this is as others have noted, the upstream lambda failing but is the intermittent nature of it normal too?

I usually kill the code and move on and its fine.

J

 

[spanky2000]

I had similar code and replaced the pre cat sensor. My scan tool lets you watch a graph of the sensor voltage. The new sensor reacted a bit quicker to steady state throttle changes and mpg improved very slightly. Also code is gone. If engine is cold on start up then the o2 sensors wont be active. Im pretty sure they only function why engine is warm.

 

[spanky2000]

PS I got all the way to the forth last word and then typo. Thanks Heineken.

 

[jinjur]

Hey Spanky....cheers for the update.
Well...its been throwing the MIL quite a bit more lately so I threw on the RSTuner with a view to looking at the O2 readings.
Was surprised to see both front and rear O2 sensors showing as a historic fault.....bit worried that there could be more to it than an O2 sensor.
Anyway.....what do you think of these graphs for an up to temp idle?

Bear in mind....I wasn't touching the throttle at all so was wondering if those "wobbles" in the signal could be candidates?

 

[spanky2000]

Hi, before I replaced my pre cat sensor my graph looked the same. It would switch between .1v and 0.7v. When I changed it for a new one the tick over graph still looked pretty similar to yours but my new one went from 0.0v to 0.8v, so more of a swing. However what really changed with the new sensor was when I held it at 3000 rpm and the graph became much better 'shaped', none of the wobbles and it switched much faster. Maybe try see what the graph looks like at 3000 rpm. I would say your sensor is ok but not perfect. The cumulative imperfection may cause the error code/light. There will be many here that know more than I though.

If yours is ok it may be it's cleanable. I've 'heard' of people cleaning them. In fact I have the one I took out currently soaking in vinegar in my shed as an experiment. I know this will probably get me struck off the forum but I'm going to hook it up shortly to see if it makes a difference. Thankfully I love the smell of vinegar so there is that as I watch the car burst into flames.

Your rear sensor looks very stable like mine too. I thought it must be broken/stuck it was so stable so I briefly swapped the sensors around and it remained the same.

 

[jinjur]

came on again last night......will try the 3k check
I also think that I might have a leak in the exhaust which I only heard last night.......if it was that mani/cat joint, could that be doing this?

J

 

[da rok]

the leak in the exhaust would confuse the post cat sensor, however this sensor should read a fairly constant voltage if your cat is working properly, if your cat is shot then it will follow fairly closely to the pre cat lambda... air leak in the exhaust or a dead cat would bring up the light...

 

[Daz...]

My EML light has been on and off for a while. I checked and the pre cat sensor was showing a constant voltage. Fitted a new one today and it's now working as it should.

 

[jinjur]

the leak in the exhaust would confuse the post cat sensor, however this sensor should read a fairly constant voltage if your cat is working properly, if your cat is shot then it will follow fairly closely to the pre cat lambda... air leak in the exhaust or a dead cat would bring up the light...

That is interesting bud.
So you think that the fact that my post cat is showing solid voltage would indicate my cat is ok and this is either a leak pre-cat or a bust sensor?

I actually think that my post cat sensor is fairly new.....i replaced one maybe 2 years ago but cant remember if it was pre or post.

J

 

[spanky2000]

I dont think the post cat effects the eml. I always understood the two sensors to be the same but the shop I got my pre cat sensor from had a Bosch for the pre and an NGK for the post. Maybe try swapping them around anyway? Im not sure but Id think the pre cat stft would show if a leak before it was causing a lean mix. You could also look at the obd readings for the map, ect, iat, throttle position and rpm. I recorded these for a two minute drive and ploted all on a graph to see if they were all acting normally. If the ecu/pcm can only vary the fuel input and its basing this on a ropey sensor reading the pre cat sensor may not have the range to be able to adjust accordingling. I am so out of my depth at this stage its not funny!

 

[Integrale1]

I had exactly the same fault and it turned out to be a failing injector on one of the cylinders, it was throwing the o2 sensor readings out making it look like it was failing. The car also had the eggy smell from the exhaust. I replaced all four and the car has never ran so smooth and responsive, might be worth having a look at the injectors.

 

[da rok]

post cat sensor would put the eml light on if there is a problem with the cat or its sensing something strange, at the end of the day they just measure the exhaust gas, unless the sensors are old and burnt they wont cause any problems, as above, if there is a leak on one of the injectors it could run rich or lean on one or more of the cylinders, over fueling can damage the cat and make it give off the sulfuric, eggs smell

pull your plugs out and have a look for signs of over fueling or under fueling...

leaks on vacuum tubes and gaskets can also cause problems

 

[Davyboy888]

I've posted another thread elsewhere but have been low on useful responses, so apologies for doing it a second time here.

I'm getting a P0130 code on my 182. I've replaced both O2 sensors. The precat is switching as expected [from around 0 to 750mV] and the post cat is sitting somewhere around 600mV-750mV... it drifts up and down a bit but doesn't go to zero or anything like that.

A few things are concerning me :

o When the car is cold, there's a terrible flat spot on acceleration... almost to the point of stalling. This seems to go away when it's warm.

o The tickover is rough and feels like it's 'hunting'... even when warm.

o When I was looking at live data the other evening, I noticed that the voltage across the pre-cat sensor was 2.5V when the engine was at ignition position 1 [i.e. switched on but engine not running].

I'd be really grateful for any help/pointers. Thanks.