Bank 1 sensor 2 high voltage came up last week and went away, just had a CEL for Cylinder 5 misfire, does this point straight to a bad o2 sensor?

[jeffmills69]

This all started around a month ago, thought I had a vacuum leak as fuel trims were high and had an intermittent rough idle, after using smoke to find a leak with no success I reset the ECM last week to reset the fuel trims just to have a suss on any other problems.. straight after doing this I got the fault code P0138 (Bank 1 sensor 2 high voltage) which went away after driving it for a day but just now I got a CEL for cylinder 5 misfire and it also was showing the stability assist had a fault and was turned off...

Would it be wise to first use a multimeter to test the supposedly faulty sensor or just replace both of the rear ones and start the car to see if it was just the sensor causing the issue?

 

[shane_3800]

You likely have a missfire.

 

[jeffmills69]

You likely have a missfire.

Meaning the misfire has been causing the o2 sensor high voltage? Whats the process in checking, test the coil pack and pull out the spark plug to have a geez?

 

[shane_3800]

Meaning the misfire has been causing the o2 sensor high voltage? Whats the process in checking, test the coil pack and pull out the spark plug to have a geez?

I can't say but the cat won't be working properly with a missfire. So you'll have to sort the missfire out first before further diagnostics.

Check the plugs first you can buy a coil tester from repco for cheap they should make a strong spark at 30k.

 

[krusing]

How may K's has it done ?

 

[Drawnnite]

Ahh the good old P0138. (have been having an issue with it myself recently on a VZ)
Would be the rear o2 sensor drivers side.

If you get a chance and can hook up to a good scan tool (ie a gscan) see what the mV reading is on all 4 o2 sensors
it should fluctuate from about 0 to say 740mV on idle. (well thats what mine were at) except that one was sitting solid at 700.
Although havent resolved it yet because just changed cats (and went extractors) and just cleaned the sensors/swapped sides but only driven it about 20kms since then.

The missfire part is interesting Shane.
Would you happen to know if that would only effect the rear o2 rather than also the front o2?

 

[jeffmills69]

I can't say but the cat won't be working properly with a missfire. So you'll have to sort the missfire out first before further diagnostics.

Check the plugs first you can buy a coil tester from repco for cheap they should make a strong spark at 30k.

Would that be an "inline spark plug tester" or a "spark plug firing tester"? Also.. do you know what should be the gap in this engine?

How may K's has it done ?

~139700km, should note NGK Iridiums were put in around 20,000 km ago

Ahh the good old P0138. (have been having an issue with it myself recently on a VZ)
Would be the rear o2 sensor drivers side.

If you get a chance and can hook up to a good scan tool (ie a gscan) see what the mV reading is on all 4 o2 sensors
it should fluctuate from about 0 to say 740mV on idle. (well thats what mine were at) except that one was sitting solid at 700.
Although havent resolved it yet because just changed cats (and went extractors) and just cleaned the sensors/swapped sides but only driven it about 20kms since then.

The missfire part is interesting Shane.
Would you happen to know if that would only effect the rear o2 rather than also the front o2?

I've got a Launch Creader CR529 which does allow me to view all 4 banks at the same time, front 2 banks fluctuate between the normal range and the back 2.. were staying the same voltage (around .600v) and they would both slowly increase when I'd increase the RPMs although this before I reset the ECM

 

[shane_3800]

Ahh the good old P0138. (have been having an issue with it myself recently on a VZ)
Would be the rear o2 sensor drivers side.

If you get a chance and can hook up to a good scan tool (ie a gscan) see what the mV reading is on all 4 o2 sensors
it should fluctuate from about 0 to say 740mV on idle. (well thats what mine were at) except that one was sitting solid at 700.
Although havent resolved it yet because just changed cats (and went extractors) and just cleaned the sensors/swapped sides but only driven it about 20kms since then.

The missfire part is interesting Shane.
Would you happen to know if that would only effect the rear o2 rather than also the front o2?

It should throw a rich code or catalyst efficiency code. But I've seen all sorts of codes show up but they are only a guide.

 

[shane_3800]

Would that be an "inline spark plug tester" or a "spark plug firing tester"? Also.. do you know what should be the gap in this engine?



~139700km, should note NGK Iridiums were put in around 20,000 km ago



I've got a Launch Creader CR529 which does allow me to view all 4 banks at the same time, front 2 banks fluctuate between the normal range and the back 2.. were staying the same voltage (around .600v) and they would both slowly increase when I'd increase the RPMs although this before I reset the ECM

Yea inline tester. So you pull the coil jam the tester into the coil and ground it to engine, battery or chassis. You wind the screw out and you can see the voltage of the spark. A good coil should make a consistent strong zap noise a weak one will make an inconsistent weaker sound zap.

Plug gap is not the only issue spark plugs can have but I think they're 1.1mm off the top of my head.

 

[krusing]

Would that be an "inline spark plug tester" or a "spark plug firing tester"? Also.. do you know what should be the gap in this engine?



~139700km, should note NGK Iridiums were put in around 20,000 km ago



I've got a Launch Creader CR529 which does allow me to view all 4 banks at the same time, front 2 banks fluctuate between the normal range and the back 2.. were staying the same voltage (around .600v) and they would both slowly increase when I'd increase the RPMs although this before I reset the ECM

Your ID Says your in Melbourne
What Area ?,
if you were close by, your welcome to call in and I would run the Autel over it.

As mentioned in an Earlier Thread,
I have always used a rule of thumb to set Plugs to 1mm,
as it makes the engines idle smoother,
and also less chance of the spark leaking/jumping to another lead, and/or to ground which could cause a misfire.