4 Ohm itís not the issue with NGK lambda
Last month i ordered a cheap universal lambda from ebay and replaced my original one. I specifically asked the seller to sent me an 8Ohm one. I installed it and it worked fine, so i ordered another one to replace the second (It's a EURO 3 car).
This time the seller sent me a different one, which measures 4 Ohm. I installed it anyway though and now my car has been working for 2 weeks perfectly and without any errors of the ECU. Also the readings are correct.
I know people who have used the NGK sensors, came to the conclusion that the errors they get were most probably due to the fact that the heater was 4 Ohm, but it seems that there must be something else that is causing the ECU errors.