Honda Accord: K24A3 ATF Degradation Causes 3rd Gear Lockup

The CM-generation Accord 5-speed automatic (BDGA/BGFA unit) relies on Honda Genuine ATF-Z1 to maintain the correct friction coefficient in the torque converter lockup clutch. As ATF degrades beyond 40,000–60,000 km intervals, the clutch material transfers onto clutch plates, raising the dynamic friction coefficient and causing the converter to shudder, grab, or slip cyclically when engaging lockup in 3rd gear (typically 60–90 km/h cruise). Many NZ/AU examples arrived with a single ATF drain-and-fill or none at all, meaning degraded fluid has been present for most of the vehicle's life. A full flush or three successive drain-and-fill cycles with fresh ATF-Z1 or DW-1 resolves the shudder in roughly 70% of cases; vehicles with worn clutch discs require a rebuild or remanufactured unit.

• Rhythmic shudder or judder at 60–90 km/h steady cruise
• Vibration felt through the floor and seat when holding highway speed
• Shudder disappears when accelerating or decelerating out of the lockup zone
• Check engine or D4 indicator light in severe cases
• Transmission hesitation or flare when upshifting 2nd to 3rd under light throttle

1. 1

   Pull ATF dipstick and check colour (healthy = cherry red; degraded = brown/black) and smell for a burnt odour.

2. 2

   Test drive at 70–80 km/h on light throttle and hold steady; shudder confirms lockup slip.

3. 3

   Ask for ATF service history.

4. 4

   If fluid is dark, budget for three successive drain-and-fills before condemning the transmission.

Parts involved: Torque converter, Clutch.

$200 to $4,200 at New Zealand independent workshop rates. That is for this job on its own, not for the car.

An estimate, in NZD, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

• “Has the ATF ever been changed, and with what fluid?”
• “Does the car shudder or vibrate at highway cruise speeds?”
• “Has a transmission shudder been diagnosed or treated before?”

The failure described above is documented in published sources — owner forums, technical service bulletins, recall notices and workshop write-ups — held in our fault database. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them, and it is a starting point for an inspection rather than a manufacturer statement.