Jeeps and some Chrysler products seem to suffer from poor electrical connectors, so inspect them thoroughly. Additionally, Jeeps have had several PCM updates on the later models. The reprogramming of the updates as well as oxygen sensor replacement for any reason is covered under the 8 year / 80,000 mile warranty. To check if the update has been completed, look next or behind the battery and there will be a serial number with the date of updating the computer. If it hasn't been done it is free for the above period.