Persistent P0430 Code After Misfire

[gilbeynut]

So a few weeks back my 2011 Volvo XC90 3.2L started revving erratically, 1 mile into my drive, when I got an ECL and the 'try slow down or shift up' message. I turned round and attempted to make it home, which I almost succeeded with until the CEL started to flash followed immediately by the car cutting out.

I pulled the codes, of which I got 2 (P0305 - Cylinder 5 Misfire, and P0350 - Ignition Coil Circuit Malfunction). On checking cylinder 5, I could see that the ignition coil had failed (it had literally melted from inside). So I replaced the ignition coil (I believe original Denso coil with 126k on it), all 6 spark plugs (Bosch Iridium) and the fuse for the ignition coil circuit (it had blown, hence the P0350 code). Whilst investigating the issue, I noted that both my fuel filter and the air intake filter where overdue replacement by 6k and 13.5k respectively (no excuses, I screwed up!). I'm pretty sure this played a part in the failure of the coil, and both have now been replaced.

One day later I got another CEL. On pulling the codes I see only a P0430 code (Catalyst System Efficiency Below Threshold (Bank 2)). This code is consistent with the cylinder 5 misfire, and has now been with me intermittently over the past 3 weeks. I clear the code to turn off the CEL, the permanent DTC will then clear after a few miles of driving (i have been scanning the codes daily), and then a couple of days later I'll get the CEL again; and so the cycle continues.

I've tried adding some CRC Guaranteed to Pass® Emissions Test Formula to a tank full of premium with no change. Before I swap out the cat, I'd like to switch the bank 1 and bank 2 pre-cat 02 sensors over. This way if the issue is with the O2 sensor then the fault should travel to Bank 1. Assuming the fault doesn't travel, I intend to do the same with the post-cat O2 sensors.

So my questions are:

1 - Are the pre-cat Bank 1 and Bank 2 sensors the same?
2 - Are the post-cat Bank 1 and Bank 2 sensors the same?
3 - Is there anything else I can check before I commit to replacing a cat?
4 - What's the mechanism by which a misfire can damage a cat?

[ggleavitt]

Someone can help with what bank is what.
For Pre-Cat, both are the same, OE PN 30756121.
For Post-Cat, drivers side is 30681335, passenger side is 30774651.
If at some point you might think about replacing these, I would suggest you use Bosch or Denso if not OE blue box. You'll find the equivalent Bosch part numbers if you do some poking around.

No idea on how you'll test it, might help to get VIDA/DICE or another Volvo centric error tool onto the car and see what else it does not like.

Good luck !

[SuperHerman]

Try cleaning your MAF first.

[gilbeynut]

Cheers for the advice guys. I know that bank 1 is cylinders 1-3, and bank 2 is cylinders 4-6. This is also consistent with bank 2 being the one giving me issues, since the misfire was on cylinder 5.

Does anyone know what the torque spec is for the no. 1 (upstream) oxygen sensors?

[ggleavitt]

Just posted some torque values for someone else on Swedespeed:
http://forums.swedespeed.com/showthread ... ost5756241

Looks like Heated O2 sensor torque is 45nm (33 ft lb).

[Stewart91]

Haveing same issues did you ever figure this one out?

[mikekoffa]

Any body come with a solution same happened to my XC90, Cylinder 5 ignition coil meltdown and then replaced with spark plugs Volvo original parts, a fuse as well needed to be replaced. the car started shaky, then starts okay after a reset to the DTS, two days engine check light went on a code pulled and Persistent P0430 Code start, so it is the same as the original post situation.
did you come with a solution for this ?
help appreciated
Mike

[oragex]

3.2 engines have problematic coolant thermostat units: these thermostats have plastic tabs inside that break at relatively low miles causing the thermostat to get stuck in the close position (most other thermostats on cars rather get stuck in open position).

Here's other examples

http://www.volvoxc.com/forums/showthrea ... -2009-XC70

viewtopic.php?f=10&t=87288&p=488609#p488609


This causes the coolant to overheat. This may not show at the temp gauge which may still remain at 12h as this gauge has a wide temperature range at 12h - from about 80C to about 105C - while the normal coolant operating temperature is near 90C. If the coolant stays for long time near 100C the top of the engine will get too hot and this can damage the ignition coils in the long term.

Because of the heat, more than one ignition coil can get faulty. Shacking engine (at idle or under acceleration) means there is a misfire - see this video how to find the culprit cylinder(s). Do NOT drive the car until the faulty coil has been replaced - this will damage the catalytic converter (you will get inefficiency or oxygen sensor codes) and possibly even the valves inside the cylinder. Note that you may or may not get a check engine light with a misfire: a misfire (shacking) can very well happen without a check engine light

[mikekoffa]

thanks oragex , I will check that 4 sure

[gilbeynut]

I'm afraid I have nothing to report. My next step would have been to replace the cat, but after doing some research on prices it just wasn't cost effective for me.

Any body come with a solution same happened to my XC90, Cylinder 5 ignition coil meltdown and then replaced with spark plugs Volvo original parts, a fuse as well needed to be replaced. the car started shaky, then starts okay after a reset to the DTS, two days engine check light went on a code pulled and Persistent P0430 Code start, so it is the same as the original post situation.
did you come with a solution for this ?
help appreciated
Mike