Diyer

Thanks for the reply nta16. Yes I have checked battery terminals and ground connections all good. I've pretty much convinced myself I need a new engine located fuse box and loom using internet and Microsoft co-pilot AI. The fault I have is apparently well known. The AI approach to diagnosis works well if you have the patience of a saint and the experience to question some of the incorrect statements it churns out . Testing and discussions with said AI took days generating huge amounts of text with lots of statements subsequently found to be untrue or misleading. For simpler problems I think the AI route would work much better. For the benefit of anyone else with this or similar issues the final conclusion from my test results generated by AI is: What the internal guidance usually says (summarised) Here’s the typical content of the internal guidance VAG techs see: Symptom: Multiple warning lamps at ignition ON No crank Symptoms improve when fusebox is warm Starter output missing intermittently ECU supply fuses show delayed activation Cause: Internal PCB crack in the engine‑bay fusebox High‑side power switch failure Thermal expansion temporarily restores continuity Diagnosis: Check ECU supply fuses for delayed or unstable voltage Check starter output for missing voltage during crank request Heat the fusebox and observe recovery Replace fusebox if confirmed Remedy: Replace engine‑bay fusebox (SB) Transfer fuses No coding required Clear DTCs

Hi I'm having "fun" trying to diagnose a cold start problem and wonder if any others from this community have experienced the same symptoms: On cold days below about 3.5 degrees C the car will not crank when key is turned to start position Various faults appear on dashboard e.g. front assist, tyre pressure etc I don't believe these are true faults If the ignition is left on for a long enough (warm up) period the car will crank and start but occasionally cuts out but then restarts ok Whilst the car engine is warm the car will restart without problem even when ambient temperature is very cold around 0 degrees I have diagnosed various components that could cause such an issue: Ignition switch on steering column is generating the start signal - ignition switch itself eliminated 645 relay is working correctly, swapped out - 645 relay eliminated Car does not have an immobiliser - eliminated The start signal is 0V at the starter solenoid when cold, 12V when warm - solenoid and starter eliminated Engine to chassis intermittent electrical connections have been eliminated using jump leads Ignition relay is not accessible to test directly (soldered in) - POSSIBLE CAUSE Coolant temperature sensor faulty - not tested yet but dashboard temperature gauge seems ok Clutch pedal pressed signal seems to be detected ok Anyone had the same sort of symptoms?

Owner of 2019 Skoda Fabia 1.0 Mk3