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OBD-II · Engine and powertrain (P)

P2BA7

NOx exceedance - empty AdBlue tank

What it means

NOx emissions may exceed limits because the AdBlue tank is empty. On vehicles with SCR, a confirmed unresolved fault may trigger reduced performance or a no-restart countdown; follow the displayed warning and the vehicle handbook.

Symptoms

  • emissions warning; an AdBlue no-start countdown may appear on SCR-equipped vehicles
  • engine warning light
  • if a no-start countdown is displayed, restarting is inhibited when it reaches zero

Likely causes, most likely first

Likely causes, most likely first
No.Cause
01AdBlue tank empty
02AdBlue level sensor fault reading empty
03refill not recognised because too little was added

What to check, step by step

  1. 01Refill with fresh AdBlue (ISO 22241); many cars need several litres before the warning clears.
  2. 02Switch the ignition on and wait, or drive a short distance, for the system to register the refill.
  3. 03If the warning stays with a full tank, check the level sensor in the tank module with a diagnostic tool.