The lean NOx trap is not storing and converting NOx as it should. Common on Euro 5 and Euro 6 diesels with a lot of urban mileage.
P2000 — also written P2OOO, P 2000, 2000 — is the OBD-II code for nox trap efficiency below threshold (bank 1). Same code, same fix: this page covers every spelling of it.
P2000 is a emissions fault code, typically costing £150–£2200 to put right in a UK garage.
What causes P2000?
- Sulphated or aged NOx trap
- Faulty NOx sensor giving false readings
- Repeated failed regeneration cycles
- Underlying EGR or injector fault raising emissions
How P2000 is fixed
- Read NOx sensor live values before condemning the trap
- Attempt a forced desulphation regeneration
- Fix any EGR or injector fault first
- Replace the NOx trap as a last resort
P2000 repair cost in the UK
Most P2000 repairs land between £150–£2200 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 P2000?
Yes, usually with reduced power. It will fail an MOT with the light on.
Urgency: medium.
What P2000 is telling you
An emissions code means a self-test run by the ECU came back outside its allowed window. That test compares what the engine was asked to do with what the sensors say happened, so a sound exhaust system with a tired sensor throws the same code as a genuinely blocked one.
On P2000 specifically — nox trap efficiency below threshold (bank 1) — 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 P2000 is diagnosed properly
Each of the known causes is ruled in or out in cost order, cheapest and most likely first. On P2000 that means working through them like this:
- Sulphated or aged NOx trap — confirmed with live data before any part is bought.
- Faulty NOx sensor giving false readings — 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.
- Repeated failed regeneration cycles — confirmed with live data before any part is bought.
- Underlying EGR or injector fault raising emissions — confirmed with live data before any part is bought.
An hour of diagnostic time on P2000 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 P2000
- Read NOx sensor live values before condemning the trap
- Attempt a forced desulphation regeneration
- Fix any EGR or injector fault first
- Replace the NOx trap as a last resort
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 P2000 is ignored
It is drivable in the short term. Left for months, though, the secondary damage is what costs money, and the original cheap cause is still there underneath it.
For reference, P2000 typically lands at £150–£2200 all-in at an independent garage in the UK — main-dealer quotes for the same job usually sit above that.
Getting P2000 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 P2000 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.