2004 Mazda MPV Problems: 7 Known Issues

On the 2002-2006 Mazda MPV 3.0L AJ-DE V6, the solid-state cooling fan control module mounted in the engine bay of second-generation MPVs is a well-known failure point. When it fails, the radiator/condenser fans either run continuously the moment the key is turned (engine never reaches operating temperature, poor fuel economy, drained battery) or stop working entirely, which lets the engine overheat in traffic even though the coolant, water pump and thermostat are fine. Because the failure mode is intermittent at first, many owners chase thermostats and water pumps before finding the module. Mazda issued a special service program covering 2002-2003 vehicles with an updated module; owners report dealers occasionally reinstalled the original-spec part number rather than the superseded one, so the failure returned.

On the 2000-2006 Mazda MPV, the second-generation MPV's automatic transmission (a 4-speed on 2000-2001 2.5L models, a Jatco 5-speed on 2002-2006 3.0L models) develops slipping, harsh shifts, and delayed engagement between 80,000-120,000 miles. The torque converter lock-up clutch wears, and the valve body solenoids stick. The transmission fluid often shows signs of degradation (dark color, burnt smell) well before problems are felt. Towing or heavy passenger loads accelerate wear.

On the 2004-2006 Mazda MPV, late second-generation MPVs use a Takata passenger frontal airbag inflator with a phase-stabilized ammonium nitrate propellant and no desiccant. Long-term exposure to high absolute humidity, high temperature and repeated temperature cycling degrades the propellant so that it burns too aggressively on deployment, over-pressurizing and rupturing the metal inflator housing and firing shrapnel into the cabin. NHTSA campaign 18V402 covers 2004 MPVs nationwide and 2005-2006 MPVs in warmer, more humid states and territories, 18V404 (filed the same day) covers 2005-2006 MPVs sold or registered in the remaining colder states, and 19V781 covers 2004-2005 MPVs whose passenger inflators were previously replaced with inflators of the same design. Mazda escalated the remaining open Takata frontal airbag recalls to a formal DO NOT DRIVE advisory in August 2024, which applies to vans that were never repaired.

On the 2002-2006 Mazda MPV, power sliding door motor, cable, or latch mechanism fails. Door may not open, not close completely, or reverse direction randomly.

On the 1990-2006 Mazda MPV, alternator fails prematurely due to heat exposure from exhaust proximity. Battery drains and warning lights come on. Can strand vehicle if battery goes flat.

On the 2000-2006 Mazda MPV, second-generation MPVs carry three catalytic converters: a main converter plus two close-coupled 'pre-cats' bolted right at the exhaust manifolds, one on the radiator side and one on the firewall side. Sitting that close to the ports, the pre-cat substrates run extremely hot and break down. The immediate symptom is a catalyst efficiency code - P0420 on earlier vehicles, P0421 (warm-up catalyst, bank 1) on Mazda's later coding - but the real hazard is that a disintegrating pre-cat can shed ceramic substrate which, on an engine that has any intake pulsation or a leaking exhaust valve, can be drawn back toward the cylinder and score the bore. The failure is almost always downstream of something else: a persistent misfire, a leaking injector, or an oil-consumption problem cooking the catalyst. Owners commonly replace the rear O2 sensor first and get the code back within a drive cycle.

On the 2002-2006 Mazda MPV 3.0L AJ-DE V6, the 3.0L AJ-DE V6 used in 2002-2006 MPVs (Mazda's version of the Ford Duratec 30) develops chronic external oil leaks as the RTV and gaskets age. The two dominant sources are the timing chain cover, where the sealant between the cover, block and heads gives up, and the valve covers, including the rubber grommets around the valve cover bolts, which split and weep. A third, less obvious source is the seal behind the water pump pulley area at the rear of the cam drive. The timing chain cover job is disproportionately expensive on this engine because all of the front-of-engine accessories, both valve covers and the oil pan must come off (along with the right halfshaft and crossmember) to extract the cover in the tight transverse bay. Left alone, oil drips onto the accessory belt and exhaust and produces the burning smell owners report.