The 1991 Pontiac Bonneville has no open NHTSA recalls. Owners report 5 recurring issue clusters, led by “Automatic transmission failure and fluid line leak.” Every Pontiac is now 15+ years old, which changes the maintenance question from 'what mileage?' to 'how old is it?' — hoses, belts, coolant, and brake fluid age out even on low-mile cars. The G6 uses GM's Oil Life System (change oil when the message appears, at most every 12 months) with Dex-Cool coolant and either the 2.4L Ecotec four or the 3.5/3.9L pushrod V6. Parts remain cheap and plentiful through GM's shared platforms — these cars are inexpensive to keep healthy if the age-based items aren't ignored.
No open recalls on file. NHTSA lists no unrepaired safety recalls for this year, make and model. A recall can be issued at any time, and a specific car can still have one open — check yours by VIN at nhtsa.gov/recalls.
What drivers and federal regulators have officially reported about the 1991 Pontiac Bonneville.
POWER TRAIN
3 NHTSA complaints · 1995-01 → 2008-12
“AUTOMATIC TRANSMISSION FAILURE, GEAR WILL NOT ENGAGE”
“AUTO TRANSMISSION HAS BEEN REPLACED TWICE”
“WHILE DRIVING APPROXIMATELY 45 MPH IN COLD WEATHER CONDITIONS, THE TRANSMISSION OIL COOLER LINE SEPARATED AND CAUSED TRANSMISSION FLUID TO LEAK EXCESSIVELY”
LATCHES/LOCKS/LINKAGES
2 NHTSA complaints · 1996-08 → 1996-12
“DOOR LOCKS STICK NOT ALLOWING DRIVER TO EXIT”
“POWER DOOR LOCKS HAD CORRORED, PASSENGERS CANNOT GET OUT OF VEHICLE, THE RELEASE BUTTON WILL NOT OPEN, HAVE TO OPEN THE DOOR FROM THE OUTSIDE”
SEAT BELTS
2 NHTSA complaints · 1996-01 → 1996-02
“FAILURE OF THE DRIVER SIDE SEAT BELT, BELT DID NOT LOCK WHEN THE CONSUMER WAS IN AN ACCIDENT”
“SHOULDER BELT GUIDE LOOP CRACKED”
SERVICE BRAKES, HYDRAULIC
6 NHTSA complaints · 1995-08 → 2003-09
“BRAKES FAILED WHILE DRIVING-PEDAL WENT TO THE FLOOR-CAUSING ACCIDENT”
“THIS CAUSED BRAKE PEDAL TO GO TO THE FLOOR WHEN BRAKES WERE APPLIED”
“SOMETIMES THE ABS BRAKES GET HARD AND THE AUTO DOES NOT STOP RIGHT”
ENGINE AND ENGINE COOLING
3 NHTSA complaints · 1997-02 → 1999-02
“WHILE DRIVING 50-60 MPH VEHICLE CUTS OFF, DOES NOT MOVE”
“VEHICLE STALLED AND CAUSED ACCIDENT, PRIOR TO RECALL”
Issues on other model years
Source: NHTSA Office of Defects Investigation (ODI). Complaint data refreshed Sep 20, 2026. Investigation data refreshed Sep 20, 2026.
We display NHTSA's record with attribution; we don't editorialize on what these complaints mean for any specific vehicle.
Critical for safety and preventing major damage
Change when the Oil Life System calls it, and at least every 12 months. On engines this age, many mechanics suggest a practical 5,000-mile ceiling — aging seals and PCV systems contaminate oil faster.
Estimated cost — typical U.S. ranges
Dealer
~$120–$160
Shop
~$85–$115
DIY
~$25–$55
Full synthetic costs more than conventional. 5-quart 0W-20 + filter is the typical bill.
Rotate every 7,500 miles. Check tire date codes too — sidewall age (6+ years) retires tires on old cars before tread wear does.
Estimated cost — typical U.S. ranges
Dealer
~$85
Shop
~$60
DIY
Free
Often free at the shop where you bought the tires — worth asking before paying.
Inspect pads, rotors, and especially brake hoses and hard lines at every service — line corrosion is a real failure mode on 15-year-old northern cars.
Estimated cost — typical U.S. ranges
Dealer
~$85
Shop
~$60
DIY
Free
Most shops do this free as a courtesy with any service. Don't pay separately if you can avoid it.
Replace every 2 years. Decade-old fluid is the hidden cause of soft pedals and seized calipers on aging GM sedans.
Estimated cost — typical U.S. ranges
Dealer
~$180–$200
Shop
~$125–$140
DIY
~$10–$25
DOT 3 or 4 — match the cap. Vacuum bleeders make this a one-person DIY.
Keeps your vehicle running smoothly and efficiently
Drain-and-fill every 45,000 miles with Dexron VI. On high-mile units that have never been serviced, prefer repeated drain-and-fills over a pressure flush.
Estimated cost — typical U.S. ranges
Dealer
~$330–$500
Shop
~$235–$355
DIY
~$60–$180
Some sealed transmissions have no dipstick — fill is precise and best left to a shop. Many drivers can still DIY drain-and-fill.
Iridium plugs at 100,000 miles on the G6's engines. Replace wires/boots on the pushrod V6 at the same time — they're brittle at this age.
Estimated cost — typical U.S. ranges
Dealer
~$285–$390
Shop
~$200–$275
DIY
~$25–$100
Iridium plugs cost more but last 100k+ miles. V6/V8 access varies wildly — some are tough.
At this age, replace the belt AND tensioner as a pair on any evidence of cracking or noise — a weak tensioner eats new belts.
Estimated cost — typical U.S. ranges
Dealer
~$195–$235
Shop
~$135–$165
DIY
~$20–$50
DIY-friendly if you can reach the tensioner. Inspect for cracks rather than swap on a strict mileage interval.
Replace every 30,000 miles — a cheap, 5-minute job on the G6.
Estimated cost — typical U.S. ranges
Dealer
~$60–$95
Shop
~$45–$70
DIY
~$15–$40
5-minute job on most cars; the airbox lid usually has clips, no tools needed.
Extends the life of your vehicle and improves comfort
Dex-Cool is rated 5 years / 150,000 miles — but on cars this old the interval is effectively 'every 5 years.' Check for intake and water-pump seepage while it's drained; use Dex-Cool only, never mixed with green coolant.
Estimated cost — typical U.S. ranges
Dealer
~$285–$330
Shop
~$200–$235
DIY
~$25–$60
Use the manufacturer-specified coolant — wrong color/chemistry can damage the cooling system.
Test the battery and alternator annually. Parasitic drains from aging body modules are common on this era of GM — a healthy battery masks them until it doesn't.
Estimated cost — typical U.S. ranges
Dealer
~$225–$390
Shop
~$160–$280
DIY
~$130–$250
Most auto-parts stores test and install batteries free with purchase. Skip the dealer markup.
Occupant deaths in fatal crashes (FARS)
115 crashes 1990–2024
How the 115 occupant deaths break down
84
driver deaths
31
passenger deaths
115
occupant deaths
Crash years covered: 1990–2024 This model year first appears in 1991 crashes. Older models have had more years on the road to appear in these crashes, so a higher count here does not by itself mean a vehicle is less safe.
FARS counts every occupant death in a fatal crash, whatever the cause — it does not mean the vehicle was at fault or defective. Counts are not adjusted for how many of each vehicle are on the road. How to read this number
FARS 2024 data is an annual report file. NHTSA revises these records when the final file is published, so this count can change.
Every vehicle has exactly one driver seat, so driver deaths line up fairly when you compare one model to another. Occupant deaths include passengers, so a three row SUV can show a higher number than a two seat car simply because it carries more people.
Both figures are plain counts, not rates. A rate would need to know how many of each vehicle are on the road, and that registration data is not public, so we do not publish rates or scores of any kind.
IIHS publishes driver death rates using this same driver only idea, paired with a registered vehicle years denominator we do not have. Their rates and these counts answer different questions, so do not read either number here as a safety rating.
Owner-reported problem signals
Separate from the federal fatality data above: complaints owners filed with NHTSA about this year and model. These are reports of problems, unverified, and are counted here only as signals.
4
complaints mentioning a crash
1
complaints mentioning a fire
Typical U.S. ranges. Actual quotes vary by shop, parts choice, and vehicle condition.
How we estimate: Dealer = OEM parts × 1.4 + labor × $165/hr. Shop = parts + labor × $115/hr. DIY = parts only.
This maintenance schedule for the 1991 Pontiac Bonneville reflects Pontiac's published service intervals and the GM Oil Life System system. Your actual service needs may vary based on driving conditions, climate, and vehicle usage. Always consult your owner's manual for model-specific recommendations.