One problem related to engine clicking and tapping noises has been reported for the 2005 Cadillac STS. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2005 Cadillac STS based on all problems reported for the 2005 STS.
The catalytic converter makes loud popping noises on passenger front side. Now is misfiring in cylinder 1 and also has unexpected gained speed without any gas peddle pushed. Gm extended the catalytic converter warranty to 200,000 miles due to converter problems. But my VIN they say isnt included. My car is a v6. My sister was the previous owner she said she never received any recall information. The website shows no open recalls but the work wasn't completed since she purchased in 2007. Gm website doesnt help at all.