1999 Saturn Coupe problems

Common 1999 Saturn Coupe problems

The Saturn Coupe 1999, also known as the S-Series, is known for its composite dent- and rust-resistant side body panels, standard third door, optional ABS, and optional traction control. However, it has also been associated with several common problems that have been reported by its owners.

One of the most common problems with the Saturn Coupe 1999 is the failure of the Engine Coolant Temperature Sensor and/or connector. This is a universal issue that affects all S-Series cars, and it is caused by Saturn's experimentation with making these sensors out of plastic, which turned out to be a huge failure. When the sensor fails, it can cause hard starting, rough idle, temperature gauge not working, awful fuel economy, poor performance, and stumbling, among many other things. The sensor has a lot to do with almost everything the computer does, and when it fails, coolant tends to leak through the sensor and damage the connector as well. If there is any sign of corrosion on the connector, it needs to be replaced.

Another common problem with the Saturn Coupe 1999 is the failure of the Throttle Position Sensor (TPS). These have a higher than normal failure rate, and the symptom is high idle, usually 1600+. If shutting off the car then restarting it causes the idle to drop back down, and the ECTS is good, it's almost definitely the TPS. The aftermarket replacements have a quality problem, so the best bet is to find a low mileage junkyard replacement or order the OE part (~$70).

The Fine wire electrode spark plugs are also known to cause problems in the S-Series cars. The S-Series has an early version of a distributorless ignition system, and it's particularly about what spark plugs to use. Without getting into too much detail, the basic requirement is the diameter of the electrode should be roughly the width of the ground. Most copper plugs fit this description. Narrow fine wire electrodes almost always cause problems, usually a p0300 and running like the car needs new plugs. The easiest thing to do here is just use the OE spark plugs, they're inexpensive and just work. NGK BKR5ESA-11 (DOHC) and BKR4ESA-11 (SOHC).

The Intake Manifold Gasket Leak in 3rd generation (00-02) SOHC (Sx1) cars is also a common problem. The symptom is sporadic or consistently high idle, p0300, p0301, or p0302. Spray carb cleaner around the intake, specifically the #1 runner, if idle changes, problem is verified.

The Crankshaft Position Sensor failure is not hugely common, but it's still a recurring failure. They usually fail when the engine is hot. You'll be driving along, and suddenly the engine dies, and won't restart until it cools. The aftermarket replacements seem to work.

The Broken coil springs in 3rd generation (00-02) cars are also a common problem. If you're doing struts, replace the springs. OE junkyard replacements from a gen-1 or gen-2 car are your best bet.

The F6 (gen 1), F5 (gen 2), F2 (gen 3) IPJB fuse block segment overheating is caused mainly by overdrawing from the 12v socket, or high power aftermarket accessories drawing from the same circuit. There will be melted plastic around the fuse. The radio, chime module, dome light, 12v socket, and fuel pump are on this circuit. You will probably know about it when the fuel pump stops working. It's possible to re-spring the connector, or just replace the entire IPJB.

The Broken Shifter cable bushing (manual trans) is made of plastic and eventually breaks. The gear shift will be loose and/or fail to shift completely. There is a stainless steel replacement here: ].

The Worn pressure regulator valve and reverse boost valve in the auto trans valve body are also known problems in the Saturn Coupe 1999. Unfortunately, this is a reality of these cars. There are no drain back holes in the pistons, which allows oil in the valve body to be pressurized when the car is shut off. This can cause the valves to wear out over time, leading to slipping, poor shifting, and other transmission problems.

In summary, the Saturn Coupe 1999 has several common problems that have been reported by its owners. These include the failure of the Engine Coolant Temperature Sensor and/or connector, Throttle Position Sensor, Fine wire electrode spark plugs, Intake Manifold Gasket Leak, Crankshaft Position Sensor, Broken coil springs, Fuse block segment overheating, Broken Shifter cable bushing, and Worn pressure regulator valve and reverse boost valve in the auto trans valve body. While these problems can be frustrating, they are generally fixable with the right knowledge and parts.

1999 Saturn Coupe car problems categorized by type of issue

After analyzing all complaints sent to the NHTSA and researching popular Saturn Coupe problems, we found that the most common problems with these 2023 model year vehicles are:

• Vehicle speed control problems
• Engine and engine cooling problems
• Air bags problems

The graph below shows statistics for all 1999 Saturn Coupe vehicle components and the number of complaints received.