1999 Cadillac STS: common problems

Owners of the 1999 Cadillac STS filed 13 complaints with NHTSA, most often about electrical system and engine and cooling. Details by component below, with sources.

Key figures

Owner complaints: 13

What fails most often

1 Electrical system 46% of all complaints
2 Engine and cooling 46% of all complaints
3 Engine 15% of all complaints
4 Steering 8% of all complaints
5 Suspension 8% of all complaints

Circle size and colour show each component’s share of NHTSA complaints. Schematic only, not a drawing of the exact model.

Electrical system: 6 complaints (46% of all).
Engine and cooling: 6 complaints (46% of all).
Engine: 2 complaints (15% of all).
Steering: 1 complaints (8% of all).
Suspension: 1 complaints (8% of all).

Symptoms owners describe

How many of the 13 NHTSA complaints mention each symptom (automatic count from complaint text; one complaint can mention several).

stalls while driving3 · 23%
steering or power steering problems2 · 15%
A/C or heater1 · 8%
overheating, coolant loss1 · 8%
loss of power / limp mode1 · 8%
smoke, burning smell, fire1 · 8%

Components owners complain about

Component	Owner complaints	involving a crash	Technical service bulletins (TSB)
Electrical system	6	0	0
Engine and cooling	6	0	0
Engine	2	0	0
Steering	1	0	0
Suspension	1	0	0

What owners report

Short excerpts of NHTSA complaints in the original wording. These are owner statements not verified by NHTSA; personal data removed.

Our sts stalled several times, but the scariest was on the highway going 65 mph. The car totally shut off, leaving the car without any power. We were able to guide the car to the side of the highway and thank goodness it started again.
Engine and cooling · 2014-09-12 · NHTSA complaint #10632731
The contact stated that while driving an unknown speed, the engine rpms increased as smoke was released from under the hood. The vehicle was towed to the mechanic who performed a diagnostic. The failure was located at the engine motor bolts, which had become disconnected due to defective metal.
Engine · 2012-10-23 · NHTSA complaint #10481981
Tl* the contact owns a 1999 cadillac sts. The contact stated that the head bolts were not the correct size for the engine and as a result, they stripped, causing the engine head to detach from the vehicle. The vehicle was taken to the dealer who diagnosed that the engine needed to be remanufactured.
Engine · 2012-08-13 · NHTSA complaint #10470401
While driving at slow speed (in town) , engine will stop entirely,.- I lose my power steering, brakes and everything else . When I get stopped, engine will start immediately. I'e had the battery checked, and am told all the connections were "fine".
Engine and cooling · 2010-02-16 · NHTSA complaint #10311128
No power steering, brakes, electric, etc. Vehicle is then difficult to start, must wait several minutes before success. Very dangerous- has happened at highway speeds several times on busy interstate. Date given is just one of at least 8 failures.
Electrical system · 2006-09-19 · NHTSA complaint #10168688
Dt*: the contact stated while driving at various speeds the vehicle stalls without warning resulting in loss of power. Afterwards, the vehicle restarts in less than a minute. The stalling occurs intermittently and has gradually become worse.
Electrical system · 2006-05-10 · NHTSA complaint #10157190
On 8/31/05 car stalled after being picked up from chevy dealer, returned to chevy dealer who found nothing. Sent to cadillac dealer who replaced some computers. Chevy dealer picked car up and drive 9 miles before car quit. Returned to cadillac dealer who replaced ignition switch. Returned to me.
Electrical system · 2005-10-11 · NHTSA complaint #10139330
1999 cadillac sts experiencing problems with water sounds behind the dashboard as well as the engine overheating. The dealer replaced the water pump but that did not resolve the problem. While driving the engine light illuminated and a warning bell sounded.
Engine and cooling · 2005-05-25 · NHTSA complaint #10122639

When owners complained

NHTSA complaints by filing year. The peak shows at what age the problems show up most.

20052
20064
20091
20102
20123
20141

Comparison

By complaint count this model year ranks 9,843 of 36,656 model years in the NHTSA data (top 27% most complained about).

On average one model year of the STS has 31 complaints (14 years in the data). This year has 13, below average.

What to check before buying

Electrical system. Scan all modules, test the battery and alternator, inspect connectors near the impact zone.
Engine and cooling. Radiator and fan after a frontal hit, coolant level and condition, overheating.
Engine. Cold start, unusual noises, oil leaks and engine codes.
Steering. Steering play, power assist, rack and tie rods after a wheel impact.

Other years of this model

Questions and answers

What are the most common problems with the 1999 Cadillac STS?

Owner complaints to NHTSA most often mention: electrical system, engine and cooling, engine. Total complaints: 13. The most frequent symptoms in complaint texts: stalls while driving (23%), steering or power steering problems (15%), A/C or heater (8%).

How many service bulletins (TSB) were issued for the 1999 Cadillac STS?

NHTSA lists 0 manufacturer service bulletins for this year. A bulletin tells dealers how to diagnose or fix a known issue; it is not a recall.

Should I buy a 1999 Cadillac STS from a US auction?

Owner complaints describe defects, not crash damage. Before bidding, check the components listed above and review the lot photos: VinWind builds a report of visible and hidden damage by VIN.

Other 1999 models

Read also

Sources: public NHTSA data (USA): service bulletins and owner complaints; YouTube: links to videos credited to their authors. Complaints are owner statements not verified by NHTSA, and describe defects rather than crash damage. Data updated 2026-11-05.