The car has tried to regenerate its NOx trap and not finished the cycle, usually because journeys are too short or another fault is interrupting it.
P2005 — also written P2OO5, P 2005, 2005 — is the OBD-II code for nox adsorber regeneration not complete. Same code, same fix: this page covers every spelling of it.
P2005 is a emissions fault code, typically costing £120–£900 to put right in a UK garage.
What causes P2005?
- Repeated short trips stopping regeneration
- Faulty temperature or NOx sensor
- Low AdBlue quality or level on SCR systems
- EGR fault raising engine-out NOx
How P2005 is fixed
- Do a 30-minute run above 2,000rpm
- Check for related sensor codes
- Verify AdBlue level and quality where fitted
- Force a regeneration at a garage
P2005 repair cost in the UK
Most P2005 repairs land between £120–£900 including parts and labour. The spread is wide because the cheap fix (a sensor, a hose, a leak) and the expensive fix (a major component) throw the same code — which is why a proper diagnosis before parts are bought saves the most money.
Can you drive with P2005?
Yes, but plan a long run soon or it will escalate.
Urgency: medium.
What P2005 is telling you
Emissions codes are logged when the ECU's own monitors cannot prove the aftertreatment system is doing its job. The light is the result of a plausibility test failing, not of a part reporting itself broken, which is why the fault is so often in the measuring circuit rather than the component being measured.
On P2005 specifically — nox adsorber regeneration not complete — the stored code records the moment that check failed, not the moment the part gave up. That gap is why two cars with the same code can need completely different repairs.
How P2005 is diagnosed properly
Each of the known causes is ruled in or out in cost order, cheapest and most likely first. On P2005 that means working through them like this:
- Repeated short trips stopping regeneration — checked with the loom flexed and the engine warm, because a wiring fault that is intermittent when cold shows itself under heat and vibration.
- Faulty temperature or NOx sensor — compared against live data and a known-good reference before it is condemned — a sensor reading the wrong thing accurately is a different fault from a dead one.
- Low AdBlue quality or level on SCR systems — checked for level and condition first, as the cheapest possible cause and a common one.
- EGR fault raising engine-out NOx — confirmed with live data before any part is bought.
An hour of diagnostic time on P2005 routinely saves more than it costs, because the alternative is buying the most expensive part on that list and hoping.
The repairs that actually clear P2005
- Do a 30-minute run above 2,000rpm
- Check for related sensor codes
- Verify AdBlue level and quality where fitted
- Force a regeneration at a garage
After the repair the code is cleared and the car is driven until the relevant readiness monitor completes, rather than handed back as soon as the light goes out. A code that has only been erased will come straight back on the next drive cycle.
What happens if P2005 is ignored
The car will usually keep going, but the fault will not clear itself and the related monitors stay incomplete — which matters if an MOT is due, because a car that has not finished its emissions self-tests can be refused.
For reference, P2005 typically lands at £120–£900 all-in at an independent garage in the UK — main-dealer quotes for the same job usually sit above that.
Getting P2005 looked at
Bob's Mechanical Repairs is an independent garage in Birnam, Dunkeld, Perthshire, with 32 years of Bob's experience on the tools. If P2005 is showing on your car, bring the scan results with you — we will read the live data ourselves, tell you which of the causes above it actually is, and price the repair before any work starts.