1999 Ford Mustang Problems

What owners report

Owners of this model year report a wide spread of issues rather than one dominant failure, with airbag non-deployment in collisions, seat belts that fail to retract or latch, and cooling-system leaks from a cracked plastic intake manifold appearing repeatedly. Many reports involve cars with relatively low mileage, suggesting several of these problems show up early as well as on higher-mileage examples; complaints peak in the late 1990s and early 2000s with a smaller tail in the 2010s.

1. 1
   Air bags

   Airbags not deploying in a crash

   • 25 complaints (12%)
   • median 69,350 mi at 6.3 yrs old (4 state mileage, few)
   • 22 mention a crash, fire or injury
   • filed 1999–2014

   Complaints describe frontal collisions at speeds from about 5 to 50 mph in which neither front airbag deployed, and owners say the dealer either could not explain it or offered no help. A few reports go the other way, with airbags deploying in a low-speed bump or with enough force to injure the driver. Several owners mention contacting the manufacturer and getting no diagnosis. Reported across a wide mileage range, from very low mileage cars to examples near 95,000 miles; many of these accounts describe the failure at the time of a collision.

   What to check: Ask whether the airbag warning lamp behaves normally (it should illuminate briefly at start-up and then go out) and whether any airbag-related diagnostic codes have been stored. A pre-purchase inspection that scans the airbag module is worth requesting.

   2 excerpts from owner complaints in NHTSA records

   “The vehicle was involved in a frontal collision while driving at 35 MPH. None of the air bags deployed upon impact. The driver sustained injuries to there neck. The vehicle is currently at the dealership. The cause of the none deployment of the air bag isn't available at this time.”

   NHTSA complaint #10080262, filed 2004-07, 46,000 miles

   “Dt: the caller said airbags deployed without warning. The caller's daughter was turning into a gas station at about 5 MPH when both front airbags deployed. She did not hit anything. Dealer and manufacturer offered no help for free. There was damage to the vehicle.”

   NHTSA complaint #10137805, filed 2005-10, 58,700 miles
2. 2
   Seat belts

   Seat belts that will not retract or latch

   • 13 complaints (6%)
   • median 33,000 mi at 5.5 yrs old (5 state mileage, few)
   • 1 mention a crash, fire or injury
   • filed 2000–2015

   Owners describe front seat belts that fail to retract into the housing or that will not latch, sometimes on both driver and passenger sides. Some say a dealer replaced the belt assembly and the problem came back; one owner reported being charged for a second repair after a recall-related fix. Others note belts that lock up too easily during ordinary driving. Reported from roughly 5,000 to about 88,000 miles, with several examples under 40,000 miles.

   Recall 99V250000

   What to check: Pull each belt fully out and let it retract several times, and check that each buckle latches and releases cleanly. Ask whether recall 99V250000 work was performed and whether any belt assemblies have been replaced.

   2 excerpts from owner complaints in NHTSA records

   “Driver's side front seat belt and passenger seat belt will not retract and locks up. It appears that the seat belt will not work in an emergency as required. This has happened numerous times.”

   NHTSA complaint #10212640, filed 2007-12, 33,000 miles

   “Both front and the rear passenger side seat belt failed to retract back into its holster when they were unfastened. Driver's side seat belt assembly was replaced, but the problem recurred.”

   NHTSA complaint #10062816, filed 2004-03, 59,000 miles
3. 3
   Engine cooling

   Coolant leaks from a cracked plastic intake manifold

   • 10 complaints (5%)
   • median 65,000 mi at 6.3 yrs old (5 state mileage, few)
   • filed 2001–2013

   Complaints describe a sweet smell of coolant, white vapor from the exhaust, and coolant leaking from a crack in the plastic intake manifold, which mechanics say requires replacement. Owners also report heater cores, water pumps, and thermostats being replaced in the same cooling system, and say the manufacturer declined assistance. A few owners mention rough running and misfire codes alongside the coolant loss. Mostly reported between about 50,000 and 75,000 miles, often noticed as a smell or visible leak while driving.

   2 related service bulletins

   What to check: Look for coolant residue or staining around the front of the engine and check the coolant level and color; ask whether the intake manifold has been replaced. A service bulletin describes an extended coverage program for the composite intake manifold, so ask whether that coverage was ever used on this car.

   2 excerpts from owner complaints in NHTSA records

   “I have a 1999 Mustang 3.8l-v6. Recently, the car began to expel a white vapor from the tailpipe when the engine is hot, along with a vibration noise. This has happened as many as 2-3 times per day. I took the car to a Ford dealer for service and replaced an air pump. This did not correct the problem. I did some research on the internet and found that many people have had the same problem which turned out to be due to blown head gaskets. …”

   NHTSA complaint #10062466, filed 2004-03, 59,000 miles

   “On january 3, 2005, the heater core on my 1999 Mustang had to be completely replaced, including the thermostat. The windows had fogged up before and the car smelled like syrup but I thought it was just vents. The heating core had to be replaced and the coolant had to be recharged and replaced also this came up to $700 dollars. On august 16 2005, 2 weeks after changing the coolant the water pump had to be replaced, once again the system had to be flushed the cost was$400. …”

   NHTSA complaint #10168452, filed 2006-09, 53,396 miles
4. 4
   Brakes

   Brake pedal going to the floor or pulling

   • 29 complaints (14%)
   • median 111,500 mi at 10.3 yrs old (2 state mileage, few)
   • 10 mention a crash, fire or injury
   • filed 1999–2014

   Owners report the brake pedal sinking to the floor and longer stopping distances, sometimes when braking on wet roads, and in some accounts a resulting collision. Others describe the car pulling to one side or jerking when the brakes are applied, and one owner reported a rear caliper problem after suspension work. Several say the dealer could not reproduce the problem. Spread from low mileage up to roughly 58,000 miles in the reports, with some failures appearing during sudden or wet-condition stops.

   What to check: Test the pedal feel at a stop with steady pressure and check for a spongy or slowly sinking pedal, plus any pull under braking. Ask about brake fluid service history and whether calipers or the master cylinder have been replaced.

   2 excerpts from owner complaints in NHTSA records

   “I took the car in to have the rear suspension knuckle replaced and my vehicle comes out with a faulty brake calliper. Something is wrong wtih the proceedure in fixing this knuckle or the technicians working on the vehicles are carless. I have read different messages on on blue oval message board about individuals have problems with their rear wheel brakes involving the caliper assembly and or rotor locking up.”

   NHTSA complaint #747966, filed 2001-07

   “While traveling at 15 MPH, the consumer had to make a sudden stop. When the brakes were applied, the pedal went to the floor and the vehicle rear ended the vehicle ahead.”

   NHTSA complaint #10017900, filed 2003-04, 58,000 miles
5. 5
   Vehicle speed control

   Cruise control will not disengage

   • 22 complaints (10%)
   • median 134,000 mi at 12.4 yrs old (3 state mileage, few)
   • 8 mention a crash, fire or injury
   • filed 1999–2014

   Owners describe cruise control that stays engaged after pressing the brake or the cancel button, sometimes requiring repeated hard pedal applications or shutting the engine off to slow down. One account traces it to a broken wire at the brake light switch. Another describes unintended acceleration after a turn, and one owner notes the vehicle was not included in a related speed control recall. Reported from about 74,000 to 165,000 miles, typically at highway speeds with cruise engaged.

   Recall 99V062001

   What to check: With the car stationary and safe, confirm the brake lights work and that pressing the brake cancels cruise on a test drive. Ask whether recall 99V062001 applied to this vehicle, since coverage by campaign depends on build details.

   2 excerpts from owner complaints in NHTSA records

   “Driving at 75 MPH on cruise control. Needed to slow down so tapped brake pedal. Cruise would not release. Hit brake pedal again. No response. Pounded brake pedal and finally cruise cancelled. Dealership found cause to be a broken wire on the brake light switch. Luckily had room in traffic to handle the problem. Next step was to hit cruise off button.”

   NHTSA complaint #10000981, filed 2003-01, 74,170 miles

   “The contact owns a 1999 Ford Mustang. The contact stated that while driving at approximately 70 MPH with the cruise control engaged, the vehicle failed to decrease in speed when the cruise control was deactivated. The contact also stated that the brake pedal was applied, but the vehicle failed to stop. The contact shut the engine off while driving in order to stop the vehicle. The vehicle was not diagnosed or repaired. …”

   NHTSA complaint #10664536, filed 2014-12, 165,000 miles

Buying note. Given the age of this model year, condition and maintenance history matter more than the typical complaint list. A pre-purchase inspection that checks the airbag system, seat belt operation, brake hydraulics, and cooling system, plus a check of open recalls by VIN, is the most useful step before buying.

Summary written with AI from a sample of 60 NHTSA complaints for this model year (picked at random, with complaints that state a mileage and recent ones taken first), then checked automatically against the source records. Where a problem shows a complaint count, every complaint for this model year was matched with fixed keyword rules (written with AI and tested against the sample), and the mileage, age and repair figures are calculated from those complaints; owners' figures are as stated, not verified. Other counts refer to the sample. The excerpts come from NHTSA's public complaint records and are unverified; capitalisation is normalised, NHTSA staff notes are removed, and shortened text ends with “…”. Something wrong? Request a correction.