Picking the correct CO detector is critical to determining if you have the CO issue in your Ford Explorer. We simply purchased a battery operated home CO detector and mounted it near the rear of the vehicle. I strongly suggest getting a detector with the digital readout *and* the ability to store peak values. A standard CO detector will only provide an audible alert when CO (measured in ppm) above a certain level is in the vehicle for extended periods of time. While this has happened with our CO detector, it often does not alert even when we smell exhaust in the vehicle. I've provided a link below to the detector we purchased. We are in no way affiliated with Amazon, Kidde, etc. This same detector can be picked up for around $20-25 at Wal-Mart, Target, and other retailers as well. You can also reset the peak value at any point in time which makes this invaluable for monitoring your exhaust/CO in your vehicle. If you have a reading, I would also recommend you take a picture of the peak reading before resetting it so you can provide proof to Ford, lawyers, or whoever else might need it in the future.