Parts for your 2015 Toyota Bb-Knock sensor

2015 Toyota bB knock sensor — what it does and how to look after it

Based on Toyota technical references — including the Toyota bB QNC20/QNC21 Repair Manual (Engine Control for 3SZ‑VE/K3‑VE), the Toyota Electronic Parts Catalogue listing for “Sensor, Knock” on QNC20/QNC21, and the engine control DTC coverage (P0325/P0328) in Toyota/Daihatsu service literature used on the related Rush/Terios — the 2015 Toyota bB is factory‑fitted with a knock sensor. It’s an essential input for the ECM, not a delete or non‑used item.

On the 2015 bB, the knock sensor is a piezoelectric listening post bolted to the block that detects detonation (knock) and lets the ECU trim ignition timing. That means better protection for the pistons and head gasket, smoother running on our 91–98 RON fuels, and the best blend of power and economy without risking engine damage. If the sensor or its wiring plays up, the ECU usually throws a Check Engine Light and a code like P0325, then pulls timing to keep the engine safe — you’ll feel it as lazier performance and higher fuel use.

It’s not a routine replacement item, but it deserves a once‑over during servicing — especially if the vehicle tows, sees hot summers, or has had oil leaks under the intake.

• Common signs: pinging under load, CEL with P0325/P0328, flat spots, unusual fuel consumption.
• Basic checks: inspect the connector and loom for oil soak, heat hardening, or chafing, confirm the sensor is torqued correctly.
• Fitment notes: the sensor sits on the block beneath the intake manifold (typically around cylinders 2–3). Access varies, some workshops remove the intake for neat access, others go from underneath.
• Replacement tips: use a quality OE‑spec sensor, install on a clean, dry boss (no sealant), and torque to about 20 N·m. Over‑tightening can skew readings.
• Aftercare: clear fault codes, check live knock counts and ignition advance with a scan tool, and take a gentle drive for the ECU to relearn.

There’s no set kilometre interval for replacement. Address it when symptoms or codes appear, or when wiring damage is found. Labour time typically ranges from under an hour to a couple of hours depending on engine variant and whether the intake needs to come off. Keeping the area dry and repairing any nearby oil or coolant leaks will help the sensor live a long, drama‑free life under the bonnet.

Popular questions about the 2015 Toyota bB knock sensor

Where is the knock sensor on a 2015 Toyota bB?
The sensor is bolted to the engine block beneath the intake manifold, roughly around cylinders two and three. On 3SZ‑VE and K3‑VE engines, most techs access it by removing parts of the intake for room, though it can sometimes be reached from below with long extensions.

Can a knock sensor be cleaned or tested?
The sensor itself is a sealed piezo unit and isn’t serviceable. Focus on the connector and loom first. Testing is done with a scan tool (looking for DTCs like P0325 and monitoring knock activity) and, in advanced cases, with an oscilloscope. If the sensor is out of spec or damaged, replacement is the fix, torqued to about 20 N·m.

Is it safe to drive with a bad knock sensor?
The ECU usually retards timing to protect the engine, so it’s generally safe for short trips, but performance and economy suffer. Prolonged driving — especially in hot weather, under load, or when towing — isn’t recommended until the fault is diagnosed and sorted.