Introduced for 2005, the Cadillac STS was not the brand’s flagship model. But it was the most expensive car in their lineup. V6, V8 and supercharged V8 powerplants were offered, along with a host of state-of-the-art (at the time) features. It wasn’t exactly a sales success, but it was one of the most advanced Cadillac’s in its day. Part of what made it so advanced were the five and six-speed automatic transmissions, which was still relatively new technology at the time. But like many cutting edge things, issues can arise. So let’s look at some of the most common Cadillac STS transmission problems, and figure out what you can do about them.
Cadillac STS Transmission Models
Cadillac STS: 5L40E Transmission
Cadillac STS: 5L50E Transmission
Cadillac STS: 6L50E Transmission
Cadillac STS Transmission Replacement Cost Estimate
Pricing varies by model. To be 100% sure on pricing, have your VIN# handy and use our Get An Estimate feature to look up your transmission by VIN#.
Replacement Cadillac STS Transmission Prices:
|Transmission||Street Smart Transmission||Autozone||Advance Auto Parts||Dealer Retail|
|5L40E (Exc. BMW)||2122||2145||2199||3618|
What are the DTC codes related to Cadillac STS transmission problems?
|P0711||Transmission Fluid Temperature Sensor Circuit Range/Performance|
|P0712||Transmission Fluid Temperature Sensor Circuit Low Input|
|P0713||Transmission Fluid Temperature Sensor Circuit High Input|
|P0714||Transmission Fluid Temperature Sensor Circuit Intermittent P0715|
|P0715||Input/Turbine Speed Sensor Circuit|
|P0716||Input/Turbine Speed Sensor Circuit Range/PerformanceÂ|
|P0717||Input/Turbine Speed Sensor Circuit No Signal|
|P0718||Input/Turbine Speed Sensor Circuit Intermittent|
|P0720||Output Speed Sensor Circuit|
|P0721||Output Speed Sensor Circuit Range/Performance|
|P0723||Output Speed Sensor Circuit Intermittent|
|P0729||Gear 6 Incorrect Ratio|
|P0730||Incorrect Gear Ratio|
|P0731||Gear 1 Incorrect Ratio|
|P0732||Gear 2 Incorrect Ratio|
|P0734||Gear 4 Incorrect Ratio|
|P0735||Gear 5 Incorrect Ratio|
|P0740||Torque Converter Clutch Circuit Malfunction|
|P0741||Torque Converter Clutch Circuit|
|P0742||Torque Converter Clutch Circuit Stuck On|
|P0744||Torque Converter Clutch Circuit Intermittent|
|P0748||Pressure Control Solenoid 'A' Electrical|
|P0750||Shift Solenoid 'A'|
|P0753||Shift Solenoid 'A' Electrical|
|P0755||Shift Solenoid 'B'|
|P0758||Shift Solenoid 'B' Electrical|
|P0767||Shift Solenoid 'D' Stuck On|
|P0850||Park/Neutral Switch Input Circuit|
|P0897||Transmission Fluid Deteriorated|
|P0973||Shift Solenoid A Control Circuit Low|
|P0976||Shift Solenoid B Control Circuit Low|
|P0977||Shift Solenoid B Control Circuit High|
|P0979||Shift Solenoid C Control Circuit Low|
|P0980||Shift Solenoid C Control Circuit High|
|P0982||Shift Solenoid D Control Circuit Low|
|P0983||Shift Solenoid D Control Circuit High|
|P0984||Shift Solenoid E Control Circuit Range/Performance|
Cadillac STS Transmission Recalls
Cadillac STS Technical Service Bulletins (TSB)
TSB 02-07-30-026 – Transmission shudder during hard acceleration – Cadillac STS 5L40E
Problem – During hard acceleration, it is not uncommon for the transmission to shudder/shake after launch. This is caused by insufficient clearance between the driveshaft attaching bolts and the transmission output shaft flange.
Solution – Install a revised transmission output shaft flange.
TSB 07-07-30-032B – Ignition key sticks, shifter binds, “shift to park” message displayed, dead battery – 5L40 Transmission | 5L50 Transmission | 6L50 Transmission | 6L80 Transmission
2007 – 2008 Cadillac SRX – 2007 – 2008 Cadillac STS – 2007 – 2008 Cadillac STS-V – 2008 Cadillac CTS
Problem – Owners may notice that the shifter seems to bind when shifting into gear or park. The ignition key may stick or be difficult to remove (SRX only). A “shift to park” message may be constantly displayed in the driver information display screen, resulting in a dead battery.
Solution – These transmission problems may be caused by out of adjustment shift linkage, a slow Brake Transmission Shift Interlock mechanism, or a Park Confirmation microswitch that is not closed.
TSB PIP4570B – Erratic torque converter clutch operation, metallic debris in the oil pan, and/or P0741, P0751 DTC – 6L50 Transmission
2008 – 2009 Cadillac CTS – 2008 – 2009 Cadillac SRX – 2008 – 2009 Cadillac STS
Problem – Drivers may notice erratic torque converter operation, which can include erratic shifting and unexpected engine stalling.
Solution – These 6L50 transmission problems can be caused by de-bonding of the TCC friction material. This can lead to internal transmission damage, possibly requiring a transmission rebuild or remanufactured transmission. At the very least the torque converter itself may need to be replaced.
Common Problems with the Cadillac STS Transmission
No forward or reverse engagement with grinding noise on initial start-up – Cadillac STS 6L50
Problem – All wheel drive equipped cars with transfer case model BW44-77, can experience a grinding noise and no forward or reverse gear engagement on initial take off. This is caused by rust damage to the transmission output shaft and transfer case input shaft, due to a lack of lubrication.
Solution – Install new transfer case input shaft and updated transmission output shaft, which has a special O-ring to trap lubricant in the splind area.
Lack of Response
Grinding or Shaking
Whining, Clunking or Humming
Refuses to Go Into Gear
Torque Converter Issues
Valve Body Issues
Transmission Noisy in Neutral
No 3rd or 4th Gear
No 1st or 2nd Gear
Trouble Codes / Check Engine Light
Can I drive with a transmission problem?
Obviously, not all Cadillac STS transmission problems will make the car undrivable. But continuing to use the car when the transmission is not working properly, can cause other components to wear out or fail prematurely.
How often does a Cadillac STS transmission need to be replaced?
As long as it is maintained properly, a Cadillac STS transmission can last for a very long time. Of course, factory design flaws and driving style do factor into the service life. But on average, we found an STS transmission can last between 130,000-180,000 miles. A correctly built remanufactured transmission however, can last considerably longer. Provided all of the OE design flaws are addressed.
How are Cadillac STS transmission issues diagnosed?
To figure out what’s actually causing your Cadillac STS transmission problems, a technician will need to connect a scan tool to the car’s OBDII port. This will allow them to read all of the trouble codes, so they can determine which components they need to inspect. Driving the vehicle may also be necessary to replicate the conditions in which the fault occurs.
How is a Cadillac STS transmission replaced?
Because the Cadillacs STS is a rear wheel drive vehicle, replacing the transmission is fairly simple. The driveshaft will have to be removed, along with other components (like the exhaust system) that may be in the way. Installation is a reverse of the removal process, but the ECU / PCM will have to be reprogrammed / reflashed to accept the new transmission using the latest GM subscription.
Recommendations for Cadillac STS transmission issues?
To save time and get back on the road faster, have your 17-digit truck VIN# handy and you can get an online quote for a reman Cadillac STS transmission here, then find a local shop using our Find a Shop guide to install it for you.
How to Solve Cadillac STS Transmission Problems
Solution A: Buy a Used Cadillac STS Transmission
Since money doesn’t exactly grow on trees, you might be tempted to go to the local junkyard and buy a used 5L40E / used 5L50E / used 6L50E transmission. They are relatively affordable, and most will come with a 30-90 day warranty. However, it is hard to know the exact condition of the internal components, so you may have the exact same problems in the near future. And that junkyard warranty probably won’t cover labor charges to fix or replace that used Cadillac STS transmission.
Solution B: Buy a Rebuilt Cadillac STS Transmission
The next most logical idea would be a rebuilt 5L40E / rebuilt 5L50E / rebuilt 6L50E transmission. Most of the time, a mechanic will take your existing gearbox, and fit it with a bunch of OE spec Cadillac STS transmission parts. This is all well and good, in theory. But taking your transmission back to the original specifications, means that all of the common failure points will be there to fail again. And that rebuilt transmission warranty may only be honored by the shop that built it. So you’ll have to pay for repairs out of pocket, if you have a breakdown while you are traveling.
Solution C: Buy a Remanufactured Cadillac STS Transmission
To get the most life out of your Cadillac STS, you may want to consider getting a remanufactured 5L40E / remanufactured 5L50E / remanufactured 6L50E from a reputable supplier. These are often upgraded to compensate for common failure points, and a nationwide warranty will allow you to be protected from transmission repair bills when you travel.
What Problem Does Your Cadillac STS Have?
Let us know the year, mileage and problem you’re having as well as any trouble (OBD) codes you’ve found. If you’ve been given a quote or paid for a repair, we’d like to hear about that too!