Hello, we are dealing with a peculiar case: we have a 2016 Panda with 9DF EU 6 light ECU in the workshop. During the first minute after switching on the ignition the engine does not start, there is no consent from the engine control unit for the motor relay. Also noticed that during this minute the fuel pump remains on and the engine revs indication is unstable it tends to give pulses, from here also noted in diagnosis 100 engine revs per pulse, for the ECU therefore the engine is started and does not give consent for the starter motor and leaves fuel pump on. After waiting for this minute, the revs needle stabilises and the signal is also stable in the diagnosis, from this moment the engine can be started regularly.

Having established that it is interference, we are looking for the possible cause and checked the engine speed signal with an oscilloscope to try to understand what is happening at that stage. We found that there is a slight disturbance of a few millivolts during this minute, after which the signal stabilises and makes us start the engine.

Are there any similar cases in this regard?