Originally Posted by tauki
Hi everyone,can anybody tell me how do I know faulty sensor & a faulty vanos
Two completely different animals.
sensor isn't truly "faulty" until you you get a MIL (check engine light) BUT, with age and miles it becomes slower until (what's known as the duty cycle) spends more time running outside of ideal mixture and the engine computer goes into default mode. That costs you fuel and power.
One of the signs of VANOS failure is a diesel engine sound, or "marbles in a can" coming from the VANOS unit. If you use only synthetic oil and change it on time, you often will not get this, but you will notice a loss of torque below 2500-3000 rpm. If you step on the gas below 2500 and let it climb WITHOUT downshifting and it feels like you got 'extra power' above 3000 rpm, your VANOS is not working as efficiently as it should.