I've got a Bank 1 Post-Catalyst Too Rich code. I also notice the dash lights and headlights flicker a little bit. Is it possible that a failing coil can cause enough of a voltage drop to cause this? On the face of it, the engine code would point to a failing coil. However, I have recently replaced my catalytic converters with Mangaflow's drop-in units (they sound and FEEL awesome). I've read that aftermarket cats can sometimes cause phantom downstream O2 issues. The flickering lights, though - that seems like it could correlate.

If not, what are other potential causes? It doesn't seem like the "bad ground" issue with the headlights, since it's ALL the lights that are flickering.

Thanks,

Ken

 

I'd start by looking hard at the power & grounds.

Then at what runs together in looms etc that might share something relevant.

Maybe something in the above could also cause a (fake?) lean code.

Depending what the above shows my guess (!) is that a bad coil couldn't be the cause - especially without flagging a coil-related code.

 

How easily can you duplicate the flickering? I'm wondering if it varies with engine RPM. What happens if you increase the total electrical load by manually turning up the HVAC fan?

My hunch is a marginal diode in the alternator creating an AC ripple. That's why I was wondering about the engine RPM. At higher RPM, the spikes are closer together and less noticeable. Adding other electrical loads tends to smooth them out, too.

Good articles:

http://www.pvv.org/~syljua/merc/TooSeptST07.pdf


https://www.motor.com/magazine-summa...tery-of-tests/


Probably a longshot, but free and easy to rule out.

Edit: Forgot to add the engine fault code may be from the nonstock cats and is not related to the flickering.

 

I have zero S-type experience or knowledge. However, on the 6-cylinder X300s a failing coil or coils will commonly cause the dashboard display to go crazy. Wildly swinging gauge needles, warning lights flashing like crazy.

I have no idea if the same can happen with other models but it seems at least plausible that it could.

Cheers
DD

 

Wow, this is very interesting. Are any fault codes set when this happens?

 

Doesn't appear to happen on an S-Type, however.

With such different electronics that is probably why.

 

Doug speaks truth concerning X300's and coil failures. Codes? "We doan need no stinkin' codes!" (with apologies to Mel Brooks)
In general, the X300 is reluctant to set codes apart from P0411 for the air pump and C1095 for the ABS pump. I've not had the flashing dash but got general misfire and 3 specific cylinder misfire codes on one of my X300's. Renewed all six plugs and the 3 offending cylinder coils and all was well. But they can misfire a lot and obviously and never set a code.

On the other hand, the S-Types can run smooth as butter and set all manner of misfire and lean codes at the same time...with perhaps a xmsn fault thrown in for good measure, if not an EPB fault to go with!

OP, I would bet on your MFS being the culprit. But hey! I'm betting with your time and money!

 

Were the catalytic converters for your S type or just aftermarket ones?

Maybe the code is related to the install?
You could swap the sensor side to side and see if the code follows.
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