Honda K24 (K-series, 2.3 and 2.4)

The 2.4-litre member of Honda's K-series — dual overhead camshafts, roller rockers to cut friction, coil-on-plug ignition with no distributor, and i-VTEC combining variable valve timing with Honda's variable lift. It is the engine under most Accords and CR-Vs of its era and has a strong reliability record.

The diagnostic subtlety is VTEC itself. Lift switching is hydraulic and depends on oil pressure and clean oil reaching the spool valve; a clogged VTEC solenoid screen produces a car that simply does not make power above the crossover, often with a stored code that names the system rather than the cause. Service history is the diagnosis more often than any component test on this engine.

Later direct-injected K24W variants add high-pressure fuel-system faults the older port-injected engines do not have, so the sub-designation matters. Exhaust cam-lobe and rocker wear on some variants is the other pattern worth knowing about, and it announces itself as a tick that follows engine speed.