Need some expert opinions regarding a strange issue that happened immediately after service.
Vehicle:
Tata Nexon Petrol 2024
Odo around 15k km
Before service:
- OEM Tata/Mobil 5W30 oil
- OEM oil filter
- OEM air filter
- Stock Bosch YR5MEO spark plugs
Today’s service work:
- Shell Helix HX8 Extra 5W30 oil
- Tata OEM oil filter
- Mahle/Purolator air filter
- NGK LKR7BIX-P iridium spark plugs installed directly from packet
- Coolant changed .
- All wheels removed, hubs/discs cleaned
- AC vents cleaned using foam cleaner spray
- Water wash
Important observations during service:
- Technicians disconnected many connectors/cables around engine bay for almost 1 hour while changing spark plugs.
Now the issue:
After service:
- Car drove perfectly fine for around 6 km back home.
- I even switched OFF and ON once after reaching home started normally.
- But after few hours, suddenly vehicle refused to start.
Current symptoms:
- Dashboard powers ON normally
- All lights bright (no dimming)
- No crank at all when pressing START button
- Only a small buzz/relay/sensor sound from engine bay
- No starter motor sound
Instrument cluster shows:
- Battery warning light
- Oil pressure warning
- Check engine light
- Brake warning
- Immobilizer/car-with-key symbol
- Seatbelt warning etc.
Questions:
Are these warning lights normal when ignition is ON but engine is not cranking?
Do these signs usually indicate a battery/ground terminal issue?
Can a loose battery terminal or grounding issue cause complete no-crank with all electronics working normally?
Could partially loose ignition coil/sensor connectors after spark plug replacement cause this?
Can moisture from AC foam cleaner entering lower dashboard area affect BCM/start interlock/brake switch and prevent cranking?
Has anyone faced similar no-crank issues after Tata service?
Could NGK LKR7BIX-P plugs themselves cause any no-crank condition?
Additional detail:
- Headlights and cluster brightness look completely normal.
- No repeated clicking sound.
- Just a small buzz/click from engine bay when START button is pressed.
Would appreciate guidance on the most likely cause before towing it back to service center.