Engine code computer dramatics

[Polehammer]

So I've got a 07 jk 3.8l 6 speed manual.... and I've had the dreaded engine warning light come on for various reasons over the past year or so. I've changed sensors etc. But I usually disconnect the battery for 10 minutes and it's solved all my problems.
Not this time... The code came up as P2308 ignition coil and this time it made the jeep run like your grandma does. On taking it to my mechanic he said the Coils buggered, ordered a new one, only to discover the exact same problem after the change over. On further investigation it was determined that my computer was toast. In to save the day was my after market national warranty company policy (said no one ever usually, but in my case they're legendary champions) who agreed to pay $1400 to fix the problem. The next issue was Jeep Australia having a severe shortage of jk computers...and this is where I'm currently at. It's looking like the only option is to send my computer in to be repaired. Has any of you had similar issues with the engine light coming on but not having any problems with the codes it's shown and if so how did you fix it?

[Mudgee hunter]

My belief of error codes is isn't always the "coil eg itself, but along its electrical path. Bad earth, bad coil lead etc. Always explore connections, volts etc. Coil relocation on XJ's is a worthy effort. Stuipid spot!

[Polehammer]

Replaced the coils and what do ya know, I got the exact same problem. It turned out to be the computer. Problem was Jeep Australia didn't have a new one. So I sent mine off to be fixed. 10 day turn around got it back andddd same problem. Turns out the fixing bloke didn't fix it. Sent it back another 10 days wait and all seemed to be sorted.

Until I went bush yesterday and did a river crossing of about 1.5ft deep and engine light is back on again. Flashing furiously at first then back to just on. Everything else seems to be going fine however. I did the key trick to get code but this time it just comes up with dashes and no code number.
If anyone has a clue as to what's going on now it'd be greatly appreciated?

I'm so over this car I'm thinking about selling it as it's just not reliable and the amount of coin I've thrown at it over the years is demoralising.

[Fishframe]

Originally Posted by Polehammer

Replaced the coils and what do ya know, I got the exact same problem. It turned out to be the computer. Problem was Jeep Australia didn't have a new one. So I sent mine off to be fixed. 10 day turn around got it back andddd same problem. Turns out the fixing bloke didn't fix it. Sent it back another 10 days wait and all seemed to be sorted.

Until I went bush yesterday and did a river crossing of about 1.5ft deep and engine light is back on again. Flashing furiously at first then back to just on. Everything else seems to be going fine however. I did the key trick to get code but this time it just comes up with dashes and no code number.
If anyone has a clue as to what's going on now it'd be greatly appreciated?

I'm so over this car I'm thinking about selling it as it's just not reliable and the amount of coin I've thrown at it over the years is demoralising.

I wouldn’t be very confident in the ECU you had fixed.

10 days, get it back, and not fixed.

Sent it back to the same person to ‘fix’? Did they tell you what went wrong with their ‘fix’ the first time, or do they not know what they are doing?

I think it is your ECU that’s still the issue. BTW, if you’re talking to them about sending it back again under warranty, I wouldn’t mention terms like ‘water crossing’ !

[humdingerslammer]

Oh by the way, I have had an 07 JKU Rubicon for nearly 14 yrs now. It's done 234K and the engine light has been on for about 12.5 years and 230K. First came on in the middle of woop woop and beyond the black stump. Shat myself. Done all the "turn it off things", checked alarm codes (none), changed oxygen sensors etc and it is still on. So I have learned to live with it. JKU goes fine!! Mostly, I think it is a gremlin.

I haven't heard of a JKU computer going apeshit though!

[Fishframe]

Originally Posted by humdingerslammer

Oh by the way, I have had an 07 JKU Rubicon for nearly 14 yrs now. It's done 234K and the engine light has been on for about 12.5 years and 230K. First came on in the middle of woop woop and beyond the black stump. Shat myself. Done all the "turn it off things", checked alarm codes (none), changed oxygen sensors etc and it is still on. So I have learned to live with it. JKU goes fine!! Mostly, I think it is a gremlin.

I haven't heard of a JKU computer going apeshit though!

My 05 TJ has the P2098 code which in the US was a TSB for a reflash.

Some reason it didn’t reach Australia. It’s an ECU thing but doesn’t cause troubles.

[st_za]

It doesn't help you diagnose and fix your issue but based on my experience as an ex-software engineer who understands a little of how ECUs work, I would be hesitant to let anyone do anything to the ECU software to make an OBD2 error go away and similarly hesitant if someone says they can diagnose and fix ECU hardware (very few people know enough about electrical engineering to fix them). And in my experience as an amateur mechanic who breaks things all too frequently and then only has OBD2 error codes to diagnose the issue, the error code is just the point where the ECU spots that something is wrong but very rarely points to the issue and always should be evaluated with a good sceptical mindset.

Software doesn't deteriorate over time like hardware does so assuming it's not a bug that was fixed in a software update (usually done by a dealership as part of a recall or service), modifying the software to accept values out of it's acceptable bounds will just hide the issue but doesn't deal with the issue itself.

Either that error code is rarely used by the ECUs of other manufacturers or they rarely encounter that issue because if you Google just "P2308", most of the results and the almost all the video results are for Jeeps/Dodges/Chryslers.

Do you know what indicated that the ECU was the cause of the issue?