Which parts fail
Components named in complaints (battery, alternator, wiring, ignition, instrument cluster, infotainment).
Mileage when the problem started
Owner reports
Selected complaints filed with NHTSA by 2004 BMW 525i owners, lightly cleaned up (personal details are redacted by NHTSA).
I was driving on my way to work and started smelling something burning. All electrical warning lights started lighting up the dash and then displays go blank. Passenger compartment was filling up with smoke coming from under glove box. I pulled over and called fire department. We disconnected battery and took to BMW. They said micro-processor located in spare tire storage area had shorted out due to water. I don't carry coolers and don't leave my trunk open when it rains. How did water get there. Bulletins show that sunroof drains get clogged and water gets into trunk and shorts out electrical. Service bulletin says if this happens, customer pay but move electrical to where it can't get wet. So BMW knows it's a problem and can cause a fire but doesn't care to cover repair. Now I'm stuck with $1000 repair for micro-processor just to be able to tell what else is burned up. …
Tl* the contact owned a 2004 BMW 525i. The contact stated that the vehicle caught fire and blew up in the garage without warning. The fire department was contacted and stated that the fire was started by the battery cable. A fire report was filed. The contact sustained injuries that required hospitalization. The vehicle was totaled and the contact's home was damaged extensively. The dealer was not contacted. The manufacturer was contacted and stated that it was not their responsibility. Six months prior to the fire, the vehicle was taken to the dealer (chapman BMW in phoenix, ar) where a recall repair of the battery cable was performed. The recall information was lost in the fire. The failure mileage was 160,000.
Tl* the contact owned a 2004 BMW 525i. While the vehicle was parked in the garage, a neighbor noticed that the vehicle was on fire. The fire department was called and extinguished the fire. The fire department stated that the fire was due to a faulty battery cable. The contact stated that the vehicle was destroyed in the fire. The contact received medical attention due to smoke inhalation. The manufacturer was not notified of the failure. The contact called an unknown local BMW dealer, but they were unable to assist. The failure mileage was 160,000.
On dec.2 my 2004 BMW 525i was sitting outside my house when it cought on fire at the fuse panel in the trunk on the right fender well. The car had been driven over 100 miles that day. My step-daughter had gotten home at midnight and parked the car. She said the car was fine when she got home at 3;30 am my neighbor knocked on my door to tell me the car was on fire. The fire department was called to put it out as ever time we would get the fire out it would spark and start again. They reported that it was a mechanical problem that caused the fire.
I started my car and turned the seat heater on low. Approx 5 mins later, smoke started coming out of the dash because the seat heater had burned two holes in the leather and smoke had circulated in my car. I stopped the car, turned it off, and turned it back on and the smoke cleared. I had contacted my local dealer and BMW na in dec 2012 because I felt the seat heaters were getting too hot - the drivers seat registered 132 degrees at that time. The dealer told me there was nothing wrong with the seat heater and BMW na never responded, outside the standard form email telling me they would get back to me. Today, the seat heater finally burned through the leather and I was fortunate not to have been burned.
Micro power module (mpm) started smoking while driving, causing erratic engine RPM, and causing smoke inside cabin and burnt electronics smell. Complete loss of radio and idrive functionality. Module is located in trunk under the spare tire. Notified BMW of north America, and they just said that the car was out of warranty and nothing could be done. I feel that this is a serious defect that could possibly start a fire. Several BMW online forums have discussed this issue. Others have remedied the problem by relocating the module to a higher place in the trunk. Most of who own these cars do not know that these vehicles have this vulnerability. Vehicle was moving in the early morning when this happened.
Tl* the contact owns a 2004 BMW 525i. The contact stated that the service indicator illuminated on the instrument panel. The vehicle was taken to the dealer where it was diagnosed that the lighting wires were zip tied together and the casing was missing. As a result, the lighting assembly on the driver and passenger side would need to be replaced. The vehicle was not repaired. The manufacturer was not made aware of the failure. The failure mileage was 190,000.
Tl* the contact owns a 2004 BMW 525i. While driving approximately 35 MPH, the vehicle stalled without warning. The vehicle failed to restart until after repeated attempts. The failure occurred whenever the vehicle was in operation. The vehicle was taken to an independent mechanic who stated that the computerized system needed to be replaced. The vehicle not repaired. The manufacturer was notified of the failure. The approximate failure mileage was 130,000.
I believe moisture collected in the bottom of the "spare tire well" in the trunk- due to changing flat tire and opening trunk in the rain. There is and electronic module at the bottom of the "spare tire well BMW stock #w61 35 6 982 347) it went on fire-because of moisture. Repair was made, module was relocated to upper left location of trunk (as was done on models after 2004 ld part is available for inspection.
Driving down the road and smelled a burning smell. Turned off the seat heater. The seat felt very hot on my lower back. When I got to work noticed that the leather was burned through on the drivers left side. You can see the exposed wiring. Very dangerous. BMW would not replace. In searching on line, I saw that this is a common situation on the seat heater element.
Electrical complaints in other 525i years
Frequently asked questions
How common are electrical problems on the 2004 BMW 525i?
NHTSA has 21 complaints about the electrical system of the 2004 BMW 525i, 25% of the model year's 84 complaints. The component named most often is ignition (2 mentions).
Is there a recall for 2004 BMW 525i electrical problems?
No. NHTSA lists no electrical system recall for the 2004 BMW 525i. If the problem is widespread, a repair may still be covered by an extended warranty or a manufacturer service bulletin — ask a dealer.
At what mileage do 2004 BMW 525i electrical problems start?
Half of the complaints with a recorded mileage happened before about 130,000 miles, and 5% before 25,000 miles.
Is it dangerous?
Owners linked 0 crashes, 9 fires and 1 injury to electrical system problems on this model year. If you notice symptoms, have the car checked before driving further.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) — owner complaints through October 20, 2026, recalls and defect investigations; fuel economy from the EPA. Complaints are unverified reports and are not proof of a defect. How we rate model years.