I have had a slight judder when the engine was cold. It has now gotten Worse and today it started shaking and I got a Reduced engine performance warning. I have for some time had a problem with the bank 2 no 2 Oxygen sensor. I have changed all 4 Oxygen sensors and tried to swap no 2 sensors from bank to bank but the problem persist. I do not believe that this is the the problem though unless someone knows better.

After the engine went into Reduced engine performance stopped the engine for a while, connected the IIDtool and checked errors in engine. There were only the two «usual» errors from the Oxygen sensor.

I have changed the supercharger water pump and swapped the wires so this is probably not that.

What can make the engine judder and trigger a Reduced engine performance without setting any error codes? 2006 Supercharged

P0159 / p0160 ? 2006 4.2 SC

Yes, I remember the P0160.

I tried resetting all codes on PCM today and the Oxygen sensor code has not yet reappeared. The reset did not remove the juddering though.

Do you have experience with this? I see you too have a 2006 SC! 2006 Supercharged

You'd need to carry out electrical tests first to confirm circuit / ecu integrity, as the sensor is not the issue. It is looking like it is just doing its job and reporting no activity being detected.

From what you describe, i would suggest the catalytic convertor is breaking down, possibly causing a a partial restriction. You could also test this theory by disconnecting the downpipe from the manifold and seeing if the juddering desists.

Pin layout for the sensor is.

Pin 1(brown/pink) is the positive feed for heating element of sensor, should see battery voltage when tested to ground (is a shared feed to bank 1 also) so that should be there unless you're also getting a bank 1 fault code.

Pin 2 (green) runs to B 47 on the ecu and should have < 1 ohm resistance.

Pin 3 (red/black) runs to B 34 on the ecu and also should show < 1 ohm resistance.

Pin 4 (white/blue) runs to B 26 on the ecu and again should show < 1 ohm resistance.

If all these test ok then i would suspect as said above, a faulty cat. 2006 4.2 SC

This is a very helpful post indeed! These tests is done on the connector to the oxygen sensor and not in the engine bay I guess?

I have searched before and was under the impression that a P0160 code would not be triggered by a faulty cat, but that it was a code only triggered when the sensor or wiring was faulty.

If it is the cat blocking the exhaust, how can this set a reduced engine performance without a code? Or is the code maybe not in the PCM but in another brain?

And, if it turns out that it is the cat, what do I do? Change it, gut it or bypass it? Are there any performance alternatives? 2006 Supercharged

I need to be sure what bank is bank 2. Can anyone enlighten me? I think RH side is bank 1 but I am not 100% sure. 2006 Supercharged

So, I searched a lot, and it seems bank 2 is LEFT. So I tested the reasmost sensor on the left side according to Spud:

Pin 1 11,6V (Ignition ON/engine OFF)
Pin 2 650 Ohm (Ignition OFF)
Pin 3 0,7 Ohm (Ignition OFF)
Pin 4 83 Ohm (Ignition OFF)

So, there seems to be a problem somewhere I guess?

I gave the cat a few hits with my hand, sure enough something is rattling inside.

There IS a history behind this, I originally had these error messsages:

P0151-1A(E

P0051-00(AA)

I then changed all 4 sensors, and immediately (or as long as it takes for te error to be set9 the P0160 error appeared). If I read it correct the P0151 and P0051 codes are for bank 1 sensor 1, whereas P0160 are for bank 2 sensor 2.

I think I will change the left cat. I am not sure if that will change the error message though, as clearly I am not getting the values I should. 2006 Supercharged

Hmmm. Firstly you will need to change out that cat if it's rattling when hit with hand. Means it's broken down and most probably is restricting exhaust gases and causing the juddering. You could always do a back pressure test or disconnect like was said before to confirm, but a rattle pretty much confirms a defective cat.

Battery voltage looks low, but could also be because you've had ignition on for some length of time while testing. Now. When you did your continuity / resistance tests i hope you had both ends of the wire disconnected. Ecu side and sensor.

Pin 2 and Pin 4 tests (650 and 83 Ohms respectively) show too high. There's something funky going on there if those readings are correct. Corroded pins spring to mind perhaps. And if not that then i'd certainly want to test those wires under load.

As for replacement cat. You're looking about £1000 new, but i also guess you most probably know that already by now!

You can buy type approved low resistance 100, 200, 400 cel etc etc cats which are conciderably cheaper but will require some fabrication to get them to fit.

As for P0151 and P0051. They're codes for pre cat sensor issues ( heating and main circuits respectively ) but are for bank 2 ( left cat ) not the right. 2006 4.2 SC

I will change the cat. There are some cheap cats on Ebay, are they trash?

https://www.ebay.com/itm/Catalytic-Convert...SwYOxeIpCm

Battery voltage does look a bit low. I had the ignition on for maybe a minute with the lights on.

Continuity test was done at the connector under the car only, I did not disconnect anything else! Where do I find the ECU and connectors? I need to measure across the line I guess, so I need a extra wire? Sorry for my ignorance...

At last, can you confirm that Bank 2 is on the LEFT side? 2006 Supercharged

Yes bank 2 is on the left side. Bank 1 will ALWAYS be the same side as cylinder 1.

Engine ecu is in the E box under the bonnet. ( large box on the left as you look at the engine )

You wont need extra wire, you just disconnect the ecu block connectors and the O2 sensor, then measure between the relevant pins to find the resistance. 2006 4.2 SC

Part numbers for oem cats.

WCD501680 O/S

WCD501690 N/S 2006 4.2 SC

Spud wrote:

Yes bank 2 is on the left side. Bank 1 will ALWAYS be the same side as cylinder 1.

Engine ecu is in the E box under the bonnet. ( large box on the left as you look at the engine )

You wont need extra wire, you just disconnect the ecu block connectors and the O2 sensor, then measure between the relevant pins to find the resistance.

My bad, apologies. I use 1.5m test leads for this kind of stuff and made the assumption without giving it thought.

So yes. If you're using standard leads you will have to substitute in some extra wire of the same gauge or thinner. Do not be tempted to front probe the connectors, especially the ecu one. Use a T pin and back probe. (You can GENTLY touch the front of the connector to make sure you have good contact on the back probed T pin) 2006 4.2 SC

Spud wrote:

Part numbers for oem cats.

WCD501680 O/S

WCD501690 N/S

N/S is left? We don't use those expressions  2006 Supercharged

So, replaced the left cat today. I was surprised that I had to cut the exhaust pipe to fit it! Also, the pipe on the cat should have been reduced to go into the original pipe but was only reduced on one side, so I had to buy a kit to expand the original pipe. It all turned out good in the end.

The problem is that the judder and reduced angine performance is still there. I checked the codes after I changed the cat but before erasing them and starting the engine, end now there was codes for misfire on several cylinders. If I try to push the throttle I get reduced engine performance and when I read the codes I get misfire on several cylinders (both banks), random misfire and misfire at start up.

I have changed spark plugs, this did not change anything. The plugs were old, but all 8 were looking the same. They might be a little too white, but I am not used to "modern" engines...

So what could it be?