The NOx sensor circuit has failed. On Euro 6 diesels this stops the AdBlue and NOx trap strategy working and often triggers a countdown to restricted starting.
P2200 — also written P22OO, P 2200, 2200 — is the OBD-II code for nox sensor circuit (bank 1). Same code, same fix: this page covers every spelling of it.
P2200 is a emissions fault code, typically costing £250–£900 to put right in a UK garage.
What causes P2200?
- Failed NOx sensor (a known wear item)
- Corroded sensor connector under the car
- Chafed wiring
- Sensor contaminated by an oil-burning engine
How P2200 is fixed
- Read NOx sensor live values
- Replace the sensor and code it where required
- Repair the loom and reseal the connector
P2200 repair cost in the UK
Most P2200 repairs land between £250–£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 P2200?
Yes for now, but some cars begin a limited-restart countdown — do not leave it for months.
Urgency: high.
What P2200 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 P2200 specifically — nox sensor circuit (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 P2200 is diagnosed properly
Each of the known causes is ruled in or out in cost order, cheapest and most likely first. On P2200 that means working through them like this:
- Failed NOx sensor (a known wear item) — 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.
- Corroded sensor connector under the car — opened, inspected for green corrosion and spread pins, and back-probed rather than unplugged, so the reading is taken with the circuit live.
- Chafed wiring — checked with the loom flexed and the engine warm, because a wiring fault that is intermittent when cold shows itself under heat and vibration.
- Sensor contaminated by an oil-burning engine — 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.
An hour of diagnostic time on P2200 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 P2200
- Read NOx sensor live values
- Replace the sensor and code it where required
- Repair the loom and reseal the connector
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 P2200 is ignored
Leaving this one is the expensive choice. The protection strategy the ECU falls into is there to limit damage, and every mile driven with the fault active is a mile the engine or gearbox spends outside its designed operating window.
For reference, P2200 typically lands at £250–£900 all-in at an independent garage in the UK — main-dealer quotes for the same job usually sit above that.
Getting P2200 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 P2200 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.