NGK Spark Plugs… Defect? Or Install Error?

… because some Volvo owners swear by them and they work fine.

Installed NGK IX Iridium Spark Plugs (p/n BKR6EIX) in my 2004 Volvo V70 2.5T AWD wagon (Engine B5254T2 R5 2.5L) with 233,600 miles(replacing Bosch plugs) Thursday afternoon. Within 3 miles of driving car threw P0600, P0863, P0P0571 & P0504, went into limp mode. I restarted the car and cleared the codes and it ran another 4 miles till I got it home. Next morning it prevented starting because of comm failure w/transmission – same codes plus U0073 (bus communication). Disconnected battery, checked CEM ECU and TCU connections, cleared codes again, reconnected battery and car ran 10 miles without codes. Next morning codes and limp mode returned multiple times.

I called my 2 Volvo specialists and they suspected CEM starting to fail and did not see any relation to new plugs. I decided to bring the car in on Monday but had the weekend to tinker – concerned this might be the end of the vehicle for me ($2k to replace CEM) I decided to remove the NGK plugs and re-install the old Bosch Platinum plugs out of desperation – the problems and codes disappeared. My car has run fine since I removed the NGK plugs and the codes have not returned after several days of driving. Voodoo? Is my car allergic? Do the plugs play a role in CEM communicating to ECU TCU? Ill pick up a new set of Bosch platinum plugs and go my merry way…

Spark Plugs: Copper Vs Iridium Vs Platinum

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