Parts for your 2019 Ford Fiesta-Knock sensor

2019 Ford Fiesta knock sensor: what it does and how to look after it

Relevant technical sources confirm the 2019 Ford Fiesta uses a knock sensor. Ford’s Workshop Manual for Fiesta powertrains (WSM, Engine Controls/Fuel—Section 303), the 2019 Fiesta Wiring Diagrams, and Ford parts catalogues listing “Sensor—Knock (12A699)” for both the 1.6L Ti‑VCT and 1.0L EcoBoost engines all show a piezoelectric knock sensor fitted to the cylinder block, monitored by the PCM and associated with DTCs P0325–P0328.

The knock sensor on a 2019 Fiesta is there to listen for knock (detonation) and help the engine computer trim ignition timing so the motor runs sweet as under all sorts of loads and fuels. On both the 1.6L Ti‑VCT and 1.0L EcoBoost, the sensor bolts to the block, “hears” vibration, and the PCM uses that signal to advance for power and economy or pull timing to protect the engine. That means better drivability, fewer rattles under load, and solid fuel efficiency on Aussie and Kiwi fuels.

It’s not a routine service item, but it is worth a look whenever the intake’s off or during big-kilometre servicing. A crook knock sensor won’t usually strand the car, but the PCM will play it safe and may feel flat as a result. Common tell-tales include:

• Check engine light with P0325, P0326, P0327, or P0328
• Sluggish acceleration or higher fuel use
• Audible pinging under load (less common if the PCM is pulling timing)

Care tips under the bonnet:

• Keep the sensor’s mounting area clean and dry, oil or corrosion can muffle the signal.
• Don’t cable‑tie aftermarket wiring to the sensor harness—electrical noise can upset readings.
• Use quality fuel, poor octane can mask issues and force constant timing pull.

Replacement is straightforward if access is clear. Disconnect the battery, remove intake ducting or the manifold as needed for access (location varies: typically mid‑block on the 1.6L, block side on the 1.0L). Unplug the connector, crack the retaining bolt, swap the sensor, and torque it to spec from the WSM (often in the 20–25 Nm range—use a torque wrench, not guesswork). Don’t use thread sealant or grease between the sensor and block, and make sure the mating face is spotless. Reconnect, clear any fault codes, then take it for a decent road test with a couple of uphill pulls so the PCM can adapt.

If they’re chasing persistent knock sensor codes, it’s smart to also check engine earths, look for intake leaks, confirm the correct spark plugs are fitted and gapped, and rule out real mechanical knock before blaming the sensor.

Where is the knock sensor on a 2019 Fiesta?

It’s bolted to the engine block. On the 1.6L Ti‑VCT it’s typically under the intake manifold near the middle of the block. On the 1.0L EcoBoost it sits on the block’s side. Access is usually from above after moving intake bits out of the way.

What are the symptoms of a failing knock sensor?

Expect a check engine light (often P0325–P0328), lazy performance, and sometimes increased fuel use. The car may feel fine at a cruise but flat up hills, as the PCM pulls timing to protect the engine.

Does a knock sensor need routine replacement?

No. It’s a fit‑and‑forget item unless it fails or is damaged. Inspect the connector and wiring during major services, and always torque a replacement correctly to ensure accurate detection.