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 1998 Mercedes-Benz ML320 owners, lightly cleaned up (personal details are redacted by NHTSA).
Tl* the contact owns a 1998 Mercedes Benz ML320. The contact stated that the vehicle was being repaired by an independent mechanic for unrelated issues when she was informed that the ignition key needed to be replaced because it no longer functioned properly. The contact was not informed as to why the failure occurred. The key was not replaced. The manufacturer was made aware of the failure and the contact was informed that in order to remedy the failure, the vehicle would need an entire new ignition system. The vehicle was not repaired. The failure mileage was 180,000. The consumer discovered during research that merceds Benz installed an inadequate computer system in her vehicle. The system would only allow eight keys to be made for the lifetime of the vehicle. …
Laundry list of failures. Jack has almost killed me while changing tire. Vehicle fell, almost hitting me but catching side of vehicle before landing on me! Hood latch has failed on a few occasions, causing hood to open while vehicle was in motion. Air mass meter failed. Has required 5 (five!) alignments in two years. When brought to dealer's attention, was told nothing was wrong. A month later requires another alignment. Alignment problems causes wear on tires, which has caused hydroplaning and loss of control of vehicle. Vehicle swerves uncontrollably when hits anything other than flat road. Transfer case motor fixed by dealer without consulting. After repair, transfer case motor failed. Dealer states owner responsible for costs. Has had repair of harmonic balancer on front of engine due to excessive heat buildup leading to oil leak and failure of belt tensioner. …
Our 1998 Mercedes m320 has been subject to unexpected stalling for some time. More recently this has increased in frequency and we have periods of loss (reduction) of power while driving. The dealer advises that we have deterioration of the catalytic converters and that there has been a recall for this problem on newer models of the m class - but not our year. We have the car at the dealer waiting for replacement parts. We are told it will be a number of weeks since the parts are in great demand. Repairs will cost over $2,000 - but the car is clearly unsafe. Most frequent stalls are starting at a light or stop sign. One concern is knowing this problem with model years just newer than ours are subject to recall while our year isn't. …
My battery was low and unknown to me the ML320 for this year loses its transponder codes in the das security module when you try to start the vehicle with a low battery. This is evidentally the third key that has lost its programming on my vehicle due to low battery voltage. Cost so far is 499 for a key, weeks waiting for the key from Germany, and 300 to program it once they recieve the key. Its a dealership only item so its very very costly. This is a known problem with mercades and checking the forums it seems that everyone that has 1998-2000 model mercades all lose their transponder codes between 129,000 and 132,000 miles no matter what.this is an obvious manufacturers defect and a known issue that should be paid for by mercades. I never had these issues with my two 2002 ml500's but I will never purchase another Benz in my life.
On my Mercedes ML320, 1998 the key refuse to start the engine. I was told at plaza motors in st,. Louis mo. That the car did not recognize the key any more. Upon my research I found that it is common problem with the ML320 series which is an engineering problem on the part of the manufacturer especially the earlier once 1998-2000 and it will cause $6700.00 to fix. I will appreciate an investigation, it's so common that a lot of people are selling their cars because of this.
Car fails to start. We had this car towed to a dealer 40 miles away from our daughter's school in mi. Needs new key system as chip not recognized and ignition system needs to be re-keyed. 8 keys have been issued to this car,(we bought it used). We only received 1 with our purchase! Everything that needs a key has to be changed. Cost estimated at $4000. We see this as a major design flaw, not a security benefit. Especiallly since their keys just quit working.
Key lock problems, would not start due to key problems, would not start because of fuel pump failures, would not start due to gas tank problems, door lock assemblies move up and down by themselves, latch on hatch door rattled, rear seat belts rattle, oil out light came on at random times, engine check light on, last the fly-by wire gas pedal went to the floor with sudden acceleration causing an accident of the vehicle with $14,000 damage.
Vehicle was in garage and it caught on fire. There was damage to garage. Dealer said fire was due to defect in battery. The cause of the fire was due to an electrical short circuit in the voltage regulator/alternator, the fire destroyed the vehicle and damaged the driveway and garage.
Car failed to start as key security chip not reconized. Needs new key. Towed to dealer who said 8 keys have already been issued to this car, must replace all locks, engine modules, etc cost $3600.00. Consider this major design flaw.
Instrument lights do not light up. Instruments cannot be seen at night including speedometer and gas gage. Potential consequences are running out of fuel or exceeding the safe speed limits because speedometer is not visible. The problem has gotten worst with time. This has been a problem since the car was new and dealers blame the problem on light bulb problems. Sometime rapping the instrument cluster cause the lights to come back on indicating that this is a problem with the connection and not the bulbs. This appears to be a defect with the bulb connections as the problem is recurring and the dealers are not truly fixing the source of the problem.
Electrical complaints in other ML320 years
Frequently asked questions
How common are electrical problems on the 1998 Mercedes-Benz ML320?
NHTSA has 21 complaints about the electrical system of the 1998 Mercedes-Benz ML320, 16% of the model year's 133 complaints. The component named most often is ignition › switch (3 mentions).
Is there a recall for 1998 Mercedes-Benz ML320 electrical problems?
No. NHTSA lists no electrical system recall for the 1998 Mercedes-Benz ML320. 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 1998 Mercedes-Benz ML320 electrical problems start?
Half of the complaints with a recorded mileage happened before about 125,000 miles.
Is it dangerous?
Owners linked 1 crash, 2 fires and 2 injuries 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.