[Mwilliams2123]

I bought a 335i a week or so ago and i have a few questions in regards to it.

The car has performance catted downpipes and a performance exhaust other then that stock all around.

The car throws a p0420 and p0430 code for cat efficiency. I know that the aftermarket cats will throw this code period my question is when these codes are thrown does it reduce the power on the engine or reduce boost pressure?

Is there a way to stop the code from being thrown aside from putting stock cats back on it?

Also i the car threw a 2ACB code for the DME main relay activation and from my searches people say it wont let the car start but my car starts and runs just fine. The code showed up a few days ago does that mean the relay is getting weak and i should replace it?

Thank you guys in advance for any info you give.

[SnapCoupe]

Originally Posted by Mwilliams2123

I bought a 335i a week or so ago and i have a few questions in regards to it.

The car has performance catted downpipes and a performance exhaust other then that stock all around.

The car throws a p0420 and p0430 code for cat efficiency. I know that the aftermarket cats will throw this code period my question is when these codes are thrown does it reduce the power on the engine or reduce boost pressure?

Is there a way to stop the code from being thrown aside from putting stock cats back on it?

Also i the car threw a 2ACB code for the DME main relay activation and from my searches people say it wont let the car start but my car starts and runs just fine. The code showed up a few days ago does that mean the relay is getting weak and i should replace it?

Thank you guys in advance for any info you give.

More than likely the previous owner had a tuner of some sort (COBB, MHD, or a piggy back like a JB4) that auto-cleared the cat code. Other than swapping the downpipe for a stock one, the only way to keep that code away is to tune the car. In stock form, the car should not decrease power if that cat-related code is being thrown.

For the DME code, I suggest clearing it and seeing if it comes back. My car will sometimes throw weird electrical codes every non and then but they typically don't come back once I clear them.

[TheMidnightNarwhal]

Originally Posted by SnapCoupe

My car will sometimes throw weird electrical codes every non and then but they typically don't come back once I clear them.

Don't want the hijack your thread OP but yeah same here. Sometimes I read the car's error memory and surprised to see some random codes. Just clear them all and they don't seem to come back.

I guess with all the eletronics it's bound to happen?

[hassmaschine]

they're not random. Whatever triggered those codes is outside the parameters BMW specified. Basically every time something is wrong, a counter (c_abc_inc_***) increments until you reach the maximum threshold (c_abc_max_***). That is when an error is stored for ***.

If the problem is not continuous, it can show as "not currently present", but that doesn't make it random at all. It just means at the moment, whatever was outside the threshold is currently showing OK. You can ignore it but it's telling you that something is failing and eventually it will stop working completely - there are many examples of this (water pump, thermostat, ELV lock, etc).

If you're familiar with the ELV lock counter reset, this is the same thing. There is a counter that increments every time the ELV lock isn't working properly, which unfortunately locks the steering wheel and prevents you from starting the car when the threshold is met (instead of simply triggering an error). Resetting the counter starts that process over (temporarily letting you drive the car again), but it doesn't actually fix the problem.. just like clearing error codes in the DME.

Probably cars like Toyota's appear to have less issues only because the car doesn't track them, so you never actually know (until the part actually fails completely). There's not so many codes because they just don't exist - it doesn't really mean it has less problems.