P0327 Knock Sensor 1 Circuit Low (Bank 1)

Do not keep driving

The voltage on this circuit is sitting near zero. Typically a short to earth, or a sensor that has failed to its low end.

Can you drive it? This class of fault can cause real mechanical damage if you keep driving on it. A persistent misfire also destroys the catalytic converter, which is the expensive part.

The definition

P0327: Knock Sensor 1 Circuit Low (Bank 1).

P0327 is a powertrain code (the engine or gearbox), defined by the SAE standard - it means the same thing on any make of car, and any generic OBD-II reader will decode it.

What to check first

Cheapest and fastest checks first:

Unplug the sensor. If the reading jumps to full scale, the wiring is fine and the sensor has failed low.
Check the sensor's 5V supply and its earth before condemning the sensor itself.

What actually causes this on a VAG

Petrol engines across VW, Audi, Skoda and SEAT carry knock sensors - small piezo "microphones" bolted hard against the side of the cylinder block that listen for pinking. Most four-cylinders have one or two; larger V engines carry more, generally split between the banks. "Circuit low, bank 1" is an electrical complaint: the ECU is seeing less signal on that sensor's wiring than it expects, and it is not telling you your engine is actually knocking. With the sensor out of action the ECU falls back to a safe, retarded ignition map, so you'll usually notice slightly less pull and slightly worse economy rather than anything alarming. Knock sensor 1 is the one covering cylinders 1 and 2, shown as G61 on a VAG scan tool; on a V engine, bank 1 is the side containing cylinder 1.

Most likely causes, in order

Damaged wiring or a poor connection in the knock sensor loom. On many of these engines the sensors sit low on the block underneath the inlet manifold, and their thin screened cables spend their life being baked and rubbed. Check the plug for oil, water and green corrosion, and wiggle the loom while watching live data - where your scan tool shows a knock sensor voltage - or simply while waiting for the fault to reappear. An intermittent that moves when you move the wire is your answer.
Sensor loose, or bolted down wrongly. A knock sensor only works if it's clamped tight against clean, bare metal, with nothing trapped under it and the bolt tightened to the figure in the workshop data. If someone has been in there recently, or the sensor was fitted with a washer or over a paint or rust patch, the signal can be well out. It costs nothing to check before you buy a part.
The sensor itself has failed. They do fail, usually after years of heat cycling. Only conclude this once the plug, the loom and the mounting have all been ruled out, because on most of these engines the sensor is the expensive bit to reach, not the expensive bit to buy.
A poor-quality or wrong-spec replacement fitted previously. If the code arrived shortly after a knock sensor was changed, suspect the part or the way it was mounted rather than the car. Cheap knock sensors and pre-made leads have a poor reputation for exactly this.

Worth knowing: On a lot of VAG engines the knock sensors live under the inlet manifold, so the labour dwarfs the parts cost. If the manifold is coming off anyway, inspect the sensor sub-harness and consider renewing it and both sensors together rather than paying for the same strip-down twice. Worth fixing rather than living with, too: while the circuit is faulty the ECU has no knock feedback to work from, so stick to the fuel grade the manufacturer specifies and avoid sustained heavy load until it's sorted - particularly on a turbocharged engine.

Reading the code is the easy part

A code names the circuit that complained. What tells you why is watching the sensor behind it while the engine runs — and that is where a code reader stops and a diagnostic tool starts.

VAGPULSE reads every module in a VW, Audi, Skoda or SEAT — not just the engine — shows the live measuring blocks behind this fault, gives you the freeze-frame conditions it was logged under, and clears it once you have fixed it. It also does what a generic OBD reader cannot on a VAG: service resets, coding, adaptations, and Stage 1–3 flashing with your original file saved first.

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Common questions

What does P0327 mean?

P0327 means Knock Sensor 1 Circuit Low (Bank 1). The voltage on this circuit is sitting near zero. Typically a short to earth, or a sensor that has failed to its low end.

Can I drive with P0327?

This class of fault can cause real mechanical damage if you keep driving on it. A persistent misfire also destroys the catalytic converter, which is the expensive part.