Dear Nissan Experts;

I am excited to find this forum where other folks have talked about the P0430 series of DTC codes - since I have had difficulty for years getting a straight answer (and complete cure) on how to attack several codes I am getting. Here are the details:

1. I get a P0430 code once or twice a day. This is increasing in frequency and I (usually) reset it after it occurs. 90% of the time, P0430 is the only code indicated when the service engine soon light comes on.

2. The other 10% of the time, P0430 is followed by P0138 and sometimes P0139 - sometimes all three are present at once. P0138 and P0139 have also come on by themselves, together, and separately. As I said before, this happens only 10% of the time when the "service engine soon" light is on.

During these malfunctions, the car does not feel any different, in any way - it runs perfectly. I haven't had the emissions tested since this has started.

I have had the ECM re-programmed twice. The last time was at least 2 - 3 years ago. I have also had numerous oxygen sensors replaced usually at least one or two per year.

I also have another issue - which may be unrelated: that's P1320 followed by P0303. This error indicates a Cylinder 3 misfire - and I suspect I need to replace the ignition assembly unit(?) - like I have in 3 other cylinders. This rarely happens, but when it does, the car temporarily feels like it's missing, and the service engine soon light sometimes blinks. This usually clears itself in less than 60 seconds.

The car has 160,000 highway miles on it and I live in Maryland. The car is well maintained, garage kept and tuned regularly. Any help on streamlining the diagnosis and letting me know the best way to communicate this to an repair facility is greatly appreciated. I'd like to narrow down the scope of this problem before taking the car in for repair (again)!

Thank you in advance for your help.

Best Regards,

Jim

P0430 refers to bad O2 sensors or bad cats. P0138/P0139 = rear O2 sensor. I would have someone test whether the problem is with a bad cat or bad O2 sensor(s) and replace accordingly.

P1320 refers to a problem with the primary ignition and P0303 refers to an engine misfire. I would have the ignition coils (packs) checked for this problem.