Hi, I just purchased my 2008 G37 and when I test drove it, it felt great, no issues. After having it delivered across the state and driving it for less than 2 hours, I had the service engine light come on. The next day, it started blinking. I replaced the spark plugs last night and found just one to be darker. Drove it this morning and it came on intermittently and then started blinking. I cleaned the throttle body and MAF sensor. It starts blinking when it goes into higher Rev and then when turns off when I cruise but still comes on here and there. I have an appointment at a shop on Monday, which I scheduled for an inspection before all this happened. What tests are the best way to figure out the source of the problem? TIA

 

Is the plug on the end a different brand? Same heat range?

 

Wow my eyes didn't even catch that 🤣. So it is a different brand - Bosche R6 which have a heat range of 9 and the rest are Denso with heat range 8. So someone did change this one out for some reason and I don't have info as to why.

 

You may have discovered the problem right there. I'd suggest replacing all of the plugs with a set of NGK Ruthenium plugs for the VQ37VHR.

 

Based on the initial post, it sounds like @Simsimmah already replaced the plugs. Wondering thought why there was the one oddball in the set he replaced as it appears someone tried to use a new plug to fix another issue.

I think the failure at higher revs indicates that there is a misfire, which may be why one plug was targeted. The plugs themselves look fairly standard.

I think he needs an OBD2 reader to see what codes are being thrown. Maybe a bad coil (code will indicate which one)? Although, the coils either work or not work as I haven't seen anyone post about intermittent coil failures.

 

I had it scanned before replacing the plugs and they were P0133 AFR sensor 1 and P0300 Multiple misfires failure. Good to know about the coils, I was wondering if those need to be replaced but the cost is adding up if that doesn't work, then new AFR sensor, then maybe something in the fuel system...so for now, I won't jump on getting new coils. Thanks for the responses!! First time I'm on my own working on cars and this forum is already much more helpful than FB 🤣

 

P0133 is O2 sensor-1 (A/F Sensor) Bank-1 (passenger side sensor - located before or in front of the cats) correct? That failure will likely cause the other code to be thrown. No modification to the factory cats?

 

It's got an after market exhaust (Manzo) but not sure how far upstream the mod starts. I'll get that info when I get the inspection tomorrow. I got it scanned again since I hadn't yet after plug replacement. Now the primary code is P0300 - too many random cylinder misfires and suggests replacing MAF sensor. Additional codes are P0420 (CAT system bank 1), P0456 EVAP system very small leak, P0133 AFR sensor 1.

 

2+ months later, I'm still chasing down the check engine light. I've replaced spark plugs, AFR sensors and o2 sensors, MAF sensors and after about 2 weeks since the MAF sensors were replaced, the check engine light turned off out of the blue. It stayed off for 4 days then came back on so I scanned it - P0133. Maybe it's whatever computer that's reading the sensor or is it time to start looking at fuel components?