What are the things that I should watch out for when buying a 2003 bmw 745li? I want to make sure I don’t buy a clunker.

With regard to the vehicle you are interested in, you want to confirm that the vehicle has NEVER been in a collision (Carfax might be helpful) and that the vehicle does NOT have any outstanding recall-related repairs. Apart from that, inasmuch as used car repair, maintenance, and restoration costs are highly dependent on the actual, as found, condition of the vehicle, the only way to get a reasonably precise estimate of costs you might face, and also to protect yourself in the transaction, is to request a pre-purchase vehicle inspection. That inspection, carried out by a certified Mechanic, dispatched to your location, will give you the EXACT data you are seeking. If you look at the just cited link for YourMechanic’s inspection service, you will see a long, long list of the vehicle systems that must be inspected as well as details of YourMechanic’s inspection methodology. You have additional valuable options, too, insofar as getting useful data about the vehicle model. The National Highway Traffic Safety Administration maintains a free database of consumer complaints, official recalls and factory service bulletins for all makes and models, by year. I encourage you to go to the NHTSA website and enter your vehicle’s specific year, make and model and review the existing reports which will give you an excellent overview of what has actually been experienced by other owners insofar as faults in the particular vehicle you are interested in. I would post the text of the reports here, but they are detailed so it will be more practical for you to view them online (it is free). In addition, "Consumer Reports" publishes system-by-system vehicle reliability data for all years, makes, and models. This data is available free in the library or on-line if you are a paid subscriber. That reliability data will give you an excellent indication of the relative likelihood that key systems on the model (and year) of interest to you will fail at greater, or lesser, frequency compared to those rates reported for other vehicles. Obviously, what you want to be looking for in that database is an indication that the vehicle "make and model year" is not a "lemon" insofar as reliability. If you are unable to access any of these resources, or desire data of a different type, please do not hesitate for a moment to re-contact YourMechanic and we will assist you further in your attempts to make a wise used vehicle purchase.

Inasmuch as used car repair, maintenance, and restoration costs are highly dependent on the actual, as found, condition of the vehicle, the only way to get a reasonably precise estimate of costs you might face, and also to protect yourself in the transaction, is to request a pre-purchase vehicle inspection. That inspection, carried out by a certified Mechanic, dispatched to your location, will give you the exact data that you need to make a fully informed, intelligent decision and minimize your risk in buying a used car. If you look at the just cited link for YourMechanic’s inspection service, you will see a long list of the vehicle systems that must be inspected as well as details of YourMechanic’s inspection methodology. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

The GM 3.8l motor has been installed in Buicks, Pontiacs and Chevrolets for decades. Particularly during the 90’s and early 00’s, these motors have used an ignition module with three coils mounted to it. This module is prone to just this type of failure. When it gets too hot, it quits working. When it cools off, it starts again. It can also display intermittent no start conditions. This is a pattern failure on this particular motor. Before I would ever replace the module, I would check for spark and injector pulse. If it just lacks spark, I would check for a crank sensor signal and replace the ignition module.

Before we get too far ahead of ourselves, do a few tests first:

Check fuel pressure. If there is none, check the fuse and the relay.
Check for injector pulse with a noid light. If this is missing, I would suspect a crank sensor. It could be a bad Power Control Module (PCM). (PCM’s are very rare to fail. I have never changed a PCM on one of these cars.)
Check for spark with a spark tester. If it is lacking spark but has injector pulse, suspect the ignition module.

If all these are present, I would take a compression test of all the cylinders. If camshaft timing is off, several of the cylinders will have significantly lower compression. Also, camshaft timing won’t start sometimes then not others; it will either start and run bad or it won’t start at all. It may sound like it is trying to start, but it won’t start.

If all of this sounds to daunting, I recommend booking a car is not starting inspection with YourMechanic

Good luck!