OBD 11 reading

[dgreaves]

after 4 trouble free years with the car the engine management light came on yesterday OBD 11 reader says PO 141 bank 1 sensor 2 does this relate to a specific lambda sensor any help appreciated.

many thank Dave Greaves

[Carolyn]

Hi, 

There are three sensors:

When looking at the engine from the rear:

Bank 1  sensor one - on the manifold to the right.(Short lead)

Bank 2  sensor one - on the manifold to the left. (Short lead)

Bank 1 sensor 2 - just after the cat and before the silencer, low down under the bumper. (Long lead)

[dgreaves]

many thanks Caroline Denso list the 2 short lead ones and  sensor pre cat 750 mm lead and post cat 850 mm lead I have ordered the post cat one hope I'm right

Dave G 

[potge]

Though you have already ordered it and most probably it will genuinely be "dead", prior to dumping the previous one you can try some easy checks:

1. Check the voltage reading of that bank (and even better all 3 of them). It should (for a start) change in the 0.1-0.7 Volt range, when on and off accel.
2. If it is totally flat, check for wiring issues.
2. Check the resistor as shown in the attached photo.
3. Try cleaning it.

[m1tch]

If you use the Torque app on your phone you can read real time data off the sensors, if you graph it, the signal should increase and decrease, if its stuck at one voltage is dead or if its slow to react its on its way out.

[dgreaves]

managed to get a genuine Denso through the trade for £54 on the ramp at my local mechanics garage in and out in 30 minutes light out that will be £40 sir! the tickover is now very smooth. sincere thanks for all your kind advice.

Dave Greaves

[kwnelson]

£94 for a Denso fitted.  My latest "2" came complete with EML shining brightly after about 20 miles, now I know Shnazzle hates resisters with a passion, BUT after 18mths living with my PFL throwing EML's willy nilly, regularly, I've got sick of chucking money at sensors,and have gone down the resister road, at £3 each,10 minutes soldering in place, my latest FL has 3 resisters in place and no EMLs, boy do they get hot, essential they are fitted to a metal base to act as a heat sink, QUESTION IS? what is the medium to long term effect.

[shnazzle]

£94 for a Denso fitted.  My latest "2" came complete with EML shining brightly after about 20 miles, now I know Shnazzle hates resisters with a passion, BUT after 18mths living with my PFL throwing EML's willy nilly, regularly, I've got sick of chucking money at sensors,and have gone down the resister road, at £3 each,10 minutes soldering in place, my latest FL has 3 resisters in place and no EMLs, boy do they get hot, essential they are fitted to a metal base to act as a heat sink, QUESTION IS? what is the medium to long term effect.

I don't remember where I covered this before but med/long term is that you be under/overfueling for the first couple of minutes every time you drive your car. 

Overfuel=cat damage, sooting, coked valves
Underfuel = sparky damage, hard starts on cold days and hot restarts

Your o2 sensor heaters are there for a reason. 
O2 sensors don't work until they've reached a high temperature (650deg or so? I forget). They basically submit bogus readings before that. This is why you car, when you first start it, is in an "open loop" fueling state. I.e. It doesn't listen to o2 sensors,bevause they're talking sh1te. 
The o2 heaters quickly heat the sensors within a few seconds, ready for thr car to enter "closed loop" fueling where it listens to o2 sensors. 

The heaters break a lot. Fact of life. If you put a resistor in, you're tricking the OBD2 on your car to think all is ok with the o2 sensors. It turns on closed loop fueling as planned. Unfortunately, your o2 sensors are still cold. So they talk crap. But your ecu listens and fuels accordingly. It doesn't know. It assumes your o2 sensors are working. 
Then all of a sudden your o2 sensors are finally hot from the exhaust gas and read correctly, at which point your ecu suddenly has to "fix" the bad fueling it has been doing. 

A "universal" denso o2 sensor is 35 quid delivered. You snip the connector off your old sensor and crimp it onto the universal sensor using the provided bits. Takes 5 mins.

So, yes o2 sensors tend to fail. Maybe once a year. 35 quid a year?... Worth it

[Petrus]

Both my dongles have appearently given up the Blue Tooth ghost, so resorted to disconnecting the battery.
The question I have is whether pulling fuse #33, the 25 amps ECU-B, has the same effect?

[shnazzle]

Both my dongles have appearently given up the Blue Tooth ghost, so resorted to disconnecting the battery.
The question I have is whether pulling fuse #33, the 25 amps ECU-B, has the same effect?

I thibk I remember having to pull both. But I thibk they're in two different fuse boxes. So... Easier to just undo the negative on the battery

[Petrus]

Ok, will do then pending arrival of a reader with cable.