Code Fail 27E5 !

[Weyne Masters]

Some one know what to do? I ve read it is knock sensor 4 fail!!

[jcolley]

Just worked on an M5 same code, was voltage regulator on alternator. Check your voltage just to be sure.

[Weyne Masters]

It doesn't make any sense ,Knock control e alternator!!!

[jcolley]

Originally Posted by Weyne Masters

It doesn't make any sense ,Knock control e alternator!!!

Knock control is handled via ionic current sensing. The DME triggers a pulse on the coil for fire it, then switches to a constant positive voltage on the plug to collect the ions generated during combustion and compares the integral of the generated current curve to a curve stored in the DME.

If the supply voltage to the coil changes for any reason during that measurement cycle, the current is thrown off, therefore the integral of the current curve is off and the DME may misunderstand that to be a problem.

Not a guarantee it's your problem, but the S85 I just fixed had no errors except that one you listed and an alternator communication error. His alternator was putting out 11.5 volts max.

It's an easy check and cost nothing, worth trying at least.

[Weyne Masters]

I believe the path is Plugs coil or o2 sensor,the car has SC and 8,000 miles oem Sparks and a lot of Octaner booster
By the way the car has P3 gauge and the voltage is about,13,8

[Patrón]

Originally Posted by Weyne Masters

I believe the path is Plugs coil or o2 sensor,the car has SC and 8,000 miles oem Sparks and a lot of Octaner booster
By the way the car has P3 gauge and the voltage is about,13,8

i'm not certain but it seems octane booster really affects our O2s. that is going to be my diagnosis. one of your O2s is jacked.