Code PO430

[Ben82]

I would say look at the O2 sensor first..... if it's gone dodgy, it's could have caused the fuel trim to go completely out of whack, and thus causing the misfires. I think if there is a problem with the sensor, the ECU will kick it back into Open Loop.

Graphing or monitoring the O2s would be a good start. However you might need to clear the codes first as it could perpetually stay in Open Loop if it thinks the sensor is buggered.

Does the engine sound like it's missing on 3 cylinders? I would guess not, if my hunch about the sensor is correct.

[abertawe1970]

Has anyone got pictures of were the O2 Sensor Bank 1 Sensor 1 Location is? Think this needs replacing due to an P0134 error.

[Mandrake]

Probably best to continue this in your original P0430 thread, rather than starting a new thread, I'll post a reply there.

[Mandrake]

In response to the question in another thread, I believe Bank 1 will be the front bank and sensor 1 will be the UPSTREAM oxygen sensor in that bank. Eg the one between the engine and the pre-cat, which is responsible for regulating the mixture on that bank.

[abertawe1970]

Has anyone got pictures of were the O2 Sensor Bank 1 Sensor 1 Location is? Think this needs replacing due to an P0134 error.

[Ben82]

Most likely the one on the left of the picture.

[abertawe1970]

Thankyou Mandrake & Ben82, sensor has been ordered and should arrive Tuesday. Are they hard to get out?

[Mandrake]

They can be rusted in pretty tight sometimes. Do you have an oxygen sensor socket ? It's a special deep reach socket with a slot down the side to allow the cable to clear the socket.

You can find them on eBay quite cheaply, something like this:

http://www.ebay.co.uk/itm/like/17146714 ... 108&ff19=0" onclick="window.open(this.href);return false;

Just make sure the one you get has a decent reach as some are a bit too short for some oxygen sensors.

Failing that you might have to resort to a very large ring spanner after the cable has been cut to undo the old one. The new one doesn't have to be really tight so can be done up with the open end of the spanner.

A spray can of rust penetrant would be good to have on hand too.

[abertawe1970]

Cheers Mandrake, no don't have the socket so will be using a spanner, and a blow lamp and lots of swearing by the looks of it.

[abertawe1970]

UPDATE! Managed to get the sensor out without any issues, and with an open ended spanner and without force.

[Mandrake]

Sounds like you had some good luck.

When we changed the oxygen sensor on my previous V6 that thing was hanging on for dear life. Ironically the special oxygen sensor socket wouldn't shift it and was just trying to round the corners off the hex but a large ring spanner did (just!) manage to get it undone.

But the question on everyone's minds is has it fixed the problem ?

Edit: Nevermind. Just noticed you said the new one wasn't expected until Tuesday.

[abertawe1970]

OK new sensor in and wired up, now I get PO130 error and misfiring again. Is there a certain way these wires colours must go? Got Grey to Grey, Black to Black but there is two whites so just joined them up?

[Mandrake]

If you're having to wire the sensor wires yourself you must have bought a cheap "universal" oxygen sensor not the OEM part. Universal sensors are sometimes poor quality or not suitable for the task they're sold for - in particular the heater wattage may not be sufficient causing the sensor not to heat up properly until the car is driven. (In which case the O2 sensor won't function at all until the car is driven some distance)

I've had that experience before where I fitted what I was told was a compatible sensor, but the heater wattage was only 1/3rd of what it should be, so it would not warm up until the car was driven - if the car was left to idle too long it would throw a fault code for the oxygen sensor.

The wire colours for a zircona sensor are here:

http://www.lambdapower.co.uk/Diagnosis/ ... ex.asp#q20" onclick="window.open(this.href);return false;

Black is signal, grey is signal ground, and the whites are power and power ground for the heater - it shouldn't matter which way around the whites are connected.

Do you have an ohm meter ? It would be worth measuring the resistance of the heater element in the O2 sensor (between the two white wires) - let us know what it is, it should be around 3 ohms.

Do you just have a basic fault code scanner or do you have a Lexia or some other scanner that can show live O2 voltage ?

To trouble shoot it you really need some way of measuring the voltage across the sensor - either via a Lexia or scan tool, or a multimeter/scope.

That lambda power site I linked to above is a great resource for understanding how an oxygen sensor should be working and how to troubleshoot it.

Also here is a video I took some time ago of the O2 voltage on my Xantia V6 from a cold start - it takes around a minute for the heater in the sensor to warm up and then you will see (at idle) the voltage switching high and low:

" onclick="window.open(this.href);return false;



Switching high and low about once a second between about 0.8v and 0.1v at idle is a sign the O2 sensor is working properly.

[abertawe1970]

I'm getting 6.8 ohms across the white wires, and I'm using a MaxiDiag OBD II diagnostic scanner for the fault codes.

[Mandrake]

Could you unplug one of the other O2 sensors at the connector and measure it's heater resistance ? 6.8 ohms sounds too high to me. Also try measuring the old one you took out.

Slightly different engine but the incompatible O2 sensor I got for my Xantia V6 had a heater resistance of 6.6 ohms, when I got the correct OEM replacement it was only 2.2 ohms...