Low signal from knock sensor.
P0327 — also written PO327, P 0327, 0327 — is the OBD-II code for knock sensor 1 low input. Same code, same fix: this page covers every spelling of it.
Knock sensor 1 circuit — low input voltage. The knock sensor is bolted to the engine block and listens for detonation ('pinking'); when the ECU sees an unrealistically low signal it stores P0327 and pulls timing to protect the engine, causing rough running and MPG loss. Usually the sensor itself, occasionally a wiring/loom fault or a dropped connector.
P0327 is a sensors fault code, typically costing £100–£500 to put right in a UK garage.
What P0327 actually feels like to drive
- Loss of power / hesitation under load, especially on hills
- MPG drop of 3–6 mpg with no obvious cause
- Idle feels slightly rough or 'lumpy' when warm
- MIL on with no misfire, no smoke and no other running fault
- Paired codes: P0328 (high input), P0332 (bank 2 low), P0300-series misfire
What causes P0327?
- Sensor failure
- Wiring
UK vehicles that throw P0327 most often
- Vauxhall Astra H/J, Corsa D, Insignia 1.4T / 1.6T / 1.8 petrol
- Ford Focus / Fiesta / Mondeo 1.0 / 1.6 EcoBoost
- VW Polo / Golf / Audi A1 / A3 1.2 / 1.4 TSI (EA111 / EA211)
- Nissan Qashqai / Juke / Micra 1.2 / 1.6 petrol (HR series)
- Toyota Yaris / Auris 1.33 / 1.6 Valvematic
- Peugeot 208 / 308 / Citroën C3 / C4 1.2 PureTech
How P0327 is fixed
- Sensor replacement
The P0327 misdiagnosis that wastes money
Some garages replace the sensor without checking anything and then wonder why the code returns. Do the two tests first. One — unplug the knock sensor connector, inspect for corrosion (very common on Vauxhall 1.4T where the sensor sits under the intake and cops all the water spray). Clean, dielectric grease, refit — 3 out of 10 clear on that alone. Two — with an oscilloscope or a decent scan tool, back-probe the sensor signal wire and tap the engine block with a spanner near the sensor while cranking; you should see a clear voltage spike. Flat line = dead sensor. Wildly-fluctuating garbage = wiring/shield fault. Three — if the sensor is buried (Ford EcoBoost 1.0 has it under the intake manifold) get a quote in writing before booking — labour can be 2–3 hours for a £30 part.
What a UK garage should charge for P0327
Diagnostic + live knock-sensor read £45–£80, sensor replacement (accessible — Vauxhall 1.4T) £95–£180 fitted, sensor replacement (buried — Ford 1.0 EcoBoost, VAG 1.2 TSI) £180–£380 fitted with intake manifold off, wiring/loom repair £80–£220. Labour From £70/hr.
P0327 repair cost in the UK
Most P0327 repairs land between £100–£500 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.
Bob's tip on P0327
On Vauxhall 1.4T A14NET the knock sensor is a known weak spot — always fit the updated part number (there's been at least two revisions) and add dielectric grease to the connector on refit or you'll be doing it again in 18 months. On Ford 1.0 EcoBoost the sensor is under the intake manifold, so if you're already having intake off for the classic coolant-hose / thermostat job, replace the knock sensor as a preventative even if it hasn't failed — the labour cost is trivial when you're already in there. On VAG 1.2/1.4 TSI never fit a pattern-part knock sensor — the signal is very sensitive to sensor calibration and the £12 eBay part often triggers the code straight back. <a href="/ask-a-mechanic-uk?code=P0327">Ask Bob about your P0327</a> for £14.99 with make, model, engine code and mileage — you'll get the honest 'sensor accessible or buried' answer and a proper price bracket before booking.
Can you drive with P0327?
Drivable.
Urgency: medium.