RX8-Pak

Ppplz..

My RX's ECU is displaying the following codes:

U0073: Control Module Comm. Bus Off
P0351: Ignition Coil 1, Circuit Malfunction

Just to make sure Ignition coil pack 1 wasn't faulty, i replaced it with a new one and still the same warning.

Since there is no Mazda dealership where i live, i would really really appreciate if you could guide me as to how to solve this issue or which part to replace.

Idling is quite rough & the 8 has lost some of its power. Should i even drive it?

HEELLPPPPPPP!!!!

otherside

There is no such code as p0351. Its not listed in the manual at all. Did the U code come back after clearing? U code could have been generated when trying to read codes with scan tool.

RX8-Pak

Thank you for your reply
You're right! P0351 does not appear in the manual. And, this is what surprised me as well since i checked it again and again myself.
The speculation here is that since coil pack 1 is fine, maybe its connector or harness or some other electrical cable might be faulty resulting in a comm. bus error and ignition pack 1 not responding properly.
This is pure speculation. I might be totally off!!

zoom44

you are totally off . the issue is directly related to the communication error. you are using a scanner to pull the codes that is not fully compatible with the rx-8s pcm. its giving a false code and communication error because it is not compatible. find one that is.

swap the coils leading to trailing and see if you have any change in drivabiltiy or idle etc. next time before changingthe coil check the harness for shorts and the plug wires

nycgps

iTrader: (1)

I know this is old as ****, I was searching for something else and this came up, might as well correct some info here.

the P0351 code DOES EXIST for JDM cars, it's removed/disabled for North American market for whatever reason.

JimmyBlack

Further to this, the codes P0351 through to P0354 refer to issues with the ignition coils A-D correspondingly (I believe A is the coil closer to the front of the car). Front to back the coils go to L1, T1 (front rotor), L2, T2 (rear rotor).
FYI, if you replace the Mazda coils with non-OE such as BHR on a JDM car, these DTCs will typically show up as a warning on the first drive cycle, and will change from warning to error on the 2nd drive cycle, triggering a CEL.

Recently I experienced erratic idle on 2nd drive cycle after BHR coils were installed. This was the first time the engine was started with coil errors (previously were warnings only). After returning to stock coils and clearing the coil errors the erratic idle disappeared. Possibly indicates some type of limp mode triggered at engine startup if coil errors are present.

5SpeedJDM

I agree with nycgps, this error code has recently appeared on my JDM and I checked with a friend who had a JDM a couple of years back.

I replaced my coils, have 4 new ones from motorking, and they come with a pretty good warrenty.

Although the engine runs as smoothly as it did prior to this happening, my car's performance has deteriorated.

Please let me know if anyone has solved this issue, and how they did it ? Do I have the cables leading to the coils checked / replaced ? or the leads going from the coil to the plugs ?