Parts for your 2005 Honda Fit-Knock sensor

2005 Honda Fit knock sensor — is it actually there?

Short answer: on the 2005 Honda Fit (GD-series, commonly sold as Jazz in Australia and New Zealand) with the L13A or L15A i-DSI engines, a knock sensor isn’t fitted from factory. This isn’t a missing piece, it’s by design.

Technical references back this up. The Honda Jazz/Fit 2002–2008 (GD) service manual’s Engine Electrical section and sensor location diagrams list no knock sensor for the L13A/L15A i‑DSI engines. The Honda Electronic Parts Catalogue (GD1/GD3) has no knock sensor or related sub-harness listed for those engines, and common aftermarket catalogues (e.g., Autodata and major sensor brand listings) don’t offer a knock sensor for a 2005 Jazz/Fit i‑DSI either. GD-series wiring diagrams also show no ECU pins populated for a knock sensor circuit on these engines.

Why didn’t Honda use one here? It comes down to how the i‑DSI engines are built and calibrated. The i‑DSI combustion strategy (two spark plugs per cylinder, efficient low-to-mid rpm torque focus) runs conservative ignition timing on regular 91–95 RON petrol, so it’s inherently less knock-prone. The ECU manages combustion using mapped ignition and fuelling, plus the usual feedback from oxygen, MAP, IAT, and coolant sensors, without needing knock feedback on these particular engines. Skipping the knock sensor also reduces cost and wiring complexity on a high-volume small car.

Worth noting for anyone wrenching: some later Fit/Jazz models with different engine variants (especially non‑i‑DSI L15A VTEC in later generations) do use a knock sensor. But for a stock 2005 GD Fit/Jazz i‑DSI, there’s nowhere to bolt one on, no connector in the loom, and no ECU strategy expecting it.

• If a scan tool shows a P0325 knock sensor code on a 2005 i‑DSI, check the ECU calibration or wiring modifications — it often points to the wrong ECU or a swap, not a failed sensor that doesn’t exist.
• When servicing, focus on good-quality fuel, clean plugs (there are eight of them on i‑DSI), and staying on top of intake and EGR cleanliness to keep combustion stable and knock-free.

Does a 2005 Honda Fit/Jazz have a knock sensor?

No — not on the GD-series i‑DSI engines (L13A/L15A) used in 2005 models. Factory manuals, parts catalogues, and wiring diagrams for these engines show no knock sensor fitted or supported by the ECU. If one appears in a parts search, it’s usually for different Honda engines or later generations.

Why would I get a knock sensor fault code (P0325) on a 2005 Fit if there isn’t one?

That usually happens after ECU swaps, incorrect tune files, or using a scan tool profile for a different engine variant. The ECU might be looking for a sensor that isn’t present. Confirm the correct ECU and calibration for the GD i‑DSI, and check that no one has modified the loom for an engine conversion.

Can I retrofit a knock sensor to my 2005 Fit/Jazz?

Practically, no. The i‑DSI block doesn’t provide a factory boss for a sensor, the loom lacks the wiring, and the stock ECU doesn’t support knock input. If knock sensing is a must-have, you’d be looking at a different engine/ECU combination or an aftermarket ECU with appropriate hardware — that’s a custom build rather than a service item.