Code 43

[mrbeanieca]

Finally got it (94 S4) scanned (thanks to Jan) and got a Code 43 check engine light. Something related to knock sensor or spark control system. The light doesn't come on all the time. It's on with a cold engine, and cycles on and off during normal driving. At highway speeds,the light is usually off.

Any ideas on how to tacktle this code? I'm suspecting it's the gas I'm using...but need some expert advice...

Thanks everyone in advance,

Erik

[Paula&Marcus]

Hi erik,
Fault code 43 has to do with the knock sensor itself and/or the knock sensor circuit.

Most likely is a faulty knock sensor.
Its also likely that the circuit (wiring) is faulty. Another possibility is that the ECM itself is faulty (very unlikely)

Here some insight:
The ECM feeds a voltage 2.5V (via port J1A11) to the knock sensor.
If the voltage is below 1.25V (=faulty sensor or short circuit)or above 3.75V (= open circuit or faulty sensor) a code 43 will be set.

Please check this simple circuit (just ONE wire 37U) and the knock sensor !
You will find a detailed trouble shooting diagram in the Lotus Service notes Section EMH.4 page 70-71

To be honest, this code has nothing to do with rocket science .. even a low skilled mechanic should be able to rectify this problem within one hour

Cheers
Marcus (www.PUKesprit.de)