What Fisha said.
Post-cat sensors pretty much only confirm the cats are working.
To see the O2 sensors as waveforms, you need an oscilloscope.
I have an ELM OBD2 reader; old but useful.
It can show the signals from the sensors jumping up and down.

Interesting when you think about how the system works...
Once you're in "closed loop", the computer takes a reading from the O2 sensor.
Sensor says "too rich"
Computer leans out the mix
Sensor says "too lean"
Computer richens it up
Sensor says...

over and over and over. Really, really fast.
Still, better than a carb. LOL. Jim
2000 NAS HSE
2005 NAS HSE

Purchased a ELM 327 ODB11 reader.
Reset everything and went a drive. Here are the readings once the EML returned whilst driving.

Short term fuel trim bank 1 2.34%
Short term fuel trim bank 2 25.00% (this pretty much never changes from this value)

Long term fuel trim bank 1 1.35%
Long term fuel trim bank 2 24.22%

Now bank 1 sensor 1 goes from 0.50v to 1.00V when driving and bank 2 sensor 1 pretty much never moves off 0.00V

Stored DTCs came up with P0030 and P0050 (O2 sensor heater control bank 1 and 2 sensor1)

DTCs detected during this driving period was P0134 Oxygen sensor circuit no activity detected (Bank 1 sensor 1)

The last bit confuses me as its bank 2 thats running rich but bank one is showing no activity detected.

Does anybody know if there are fuses related to the heating element side of the O2 sensors, and if so where they may be?
Help appreciated, Fraser

Anybody?


Fraser

Sounds like someone already changed over the sensor connectors ??? Anyway, check the wiring first but it sounds like you have to replace at least the sensors on one side. As far as I am aware these sensors are not "fused" and the heating element is inside the sensor.

Try the downstream sensor first, replace it with a new sensor and see if it comes up. MY 2010 5.0 SC Galway green and sand interior!!
Have the Faultmate MSV2 Extreme to be tinkering with the settings etc. !!

Sorry, missed the post. Don't understand the P-error, but the other data makes a bit of sense.


Readings of bank 1 are fine ... anything upto about 10% fuel trim is normal operations.

Readings of bank 2 - its trying to add fuel, lots of, to the point it knows something isn't right ... which matches with the sensor reading of 0V. IIRC a normal O2 reading of perfect fuel mix is about 0.45V ... and the readings should jump above and below that. Above 0.45V is rich, and below is lean. 0V is a lean reading so the system is adding more fuel, and cause its remaining at 0V, it just keeps adding and adding.

Just to double check, are you seeing valid throttle position, air flow and air inlet temperature readings as well?


Its pointing at an o2 fault to me at the moment. V8 or else ...

Thanks for the replies gents. Reset the faults and tried a genuine O2 sensor upstream of the cat on bank 2. It was then reading 0.430v and the fuel trim went to zero. But the fuel trim and V reading didnt move at all under revs or anything. Bank 1 still bouncing back and forth as normal. Switched the ignition off then restarted it within a minute the engine management light came on and engine start to feel rough again. Bank 2 still reading the same. Fault read as no activity detected.
Conclusiuons so far are, it cant be the sensor upstream of the cat as ive now tried 3 different sensors,and MAF new plugs.

'edit'
Plugged the IIDtool into it, these are faults it brought up.
412-o2 sensor circuit upstream fault
405-o2 sensor heater circuit bank 2 upstream fault
40D-o2 sensor heater circuit bank 1 upstream fault

Any ideas where to try next anyone?


The car is returning 11mpg with this fault and will be getting sold if it cant be sourced. Truely great cars when they work but could never be regarded as top class cars with the amount of faults and reliability issues they have, thats in general not just my current experience.

Fraser

Last edited by KARMANN on 5th Oct 2012 6:11pm. Edited 1 time in total

Gotta be worth a trip to the Indy I would say....

Ok so decided to trace the wires for the O2 sensor on bank 2 sensor 1. Traced it back to the ECUs in the front left of the engine bay. Whilst having a good look in there I found some 30amp fuses. Although they looked ok I decided to remove them and check continuety. One of them had blown, replaced this started the car and hey hoe not MIL light and no over fueling, connected compter up and getting bang on values for everything-Job done!!
So lesson learned, there is atleast one sensor that takes to do with the O2 sensors.

There are so many posts on so many different forums regarding the left bank running rich with allot of parts being replaced, just as I also did without any success. Hope google brings them all here.

Regards Fraser

Hi guys I know this is a realy old thread but after getting the engine light on over the weekend and fault codes p154 p134
I decided to take a look on the forum and came across this thread I checked the the said fuses and one was blown
I replaced the fuse and now back to normal what a great place full fat RR is just goes to show how helpful it is no matter old the thread is

 1994 softail full stars n stripes custom harley davidson

Good news mate, and a nice cheap fix.... wish all faults were just a blown fuse...!!! Pete
__________________________________________________
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i wonder why the fuse blew Phil? ... - .- -.




Y. O. L. O.
.

I'm not sure Stan but Sunday from cold had to have the wheels spinning away from the house as a car was trying to kill me
It's only 30 on my road but they think it's a race track
After that the light came on hope I've cured it though and I'm also glad it was a quick fix pete


Phil 1994 softail full stars n stripes custom harley davidson