2004 V70 T Seems NGK IX Iridium Spark Plugs Caused/contribute to CEM Codes Limp Mode Topic is solved

[KLR142]

The shop I work at has used those plugs on all turbo Volvos that they fit with for over 10 years without issue. There may have been a single bad plug here or there, but they are good plugs and work on P2 Volvos(excluding P2R models that have the longer threads).

[cn90]

1+,

Actually the cause in this thread was NOT Iridium spark plug issues. The root cause for this problem was updated in another thread!

So YES, NGK Iridium is safe to use. I use it.

[erikv11]

What was the root cause, or can someone point to the thread?

[dono]

1+,

Actually the cause in this thread was NOT Iridium spark plug issues. The root cause for this problem was updated in another thread!

So YES, NGK Iridium is safe to use. I use it.

OP here - I can tell you that the plugs in my case were a contributing factor - I changed them out for Bosch and the problem went away. I suspect the primary cause is that my CEM is old and probably has issues that dont allow it to tolerate something about the NGKs. This appears to be specific to my vehicle as others have reported long term use of the NGK Iridium spark plugs. Id be curious to see which thread the 'root cause' for this was 'updated'

[precopster]

I've been using NGK BKR6E on all our turbo Volvos for about 6 years. Also fitted them to a 1998 V70R and everything Volvo turbo up to 2006 with no issues.

I always check gaps, no problems except where I fitted a set to a non turbo 1999 V70 (had nothing else on hand) which is supposed to have triple electrode plugs. The single electrode plugs wore out and had very large gaps within 20,000kms causing misfires.

Haven't tried iridiums or platinums as yet, though NGK's Aussie web site calls for platinums where the USA site lists standards and platinums....interesting.

[jimmy57]

Surface gap plugs and the older Bosch with the teeny weenie platinum wire electrode are the only plugs I have seen these engines not like when they are at correct gap. They don't like Volvo correct for application plugs if someone gaps them wider. The CEM doesn't give a hoot about plugs but if you have suppression issues caused by plugs of any brand or type and if the coils have an issue where internal arc on primary from too high secondary voltage then a lot of things in electrical system can have issues randomly.

[abscate]

He tried it and reports back....

[dono]

I should note a recent dying battery caused some pretty wacky ECM, 'start prevented' codes that disappeared when I replaced the battery.