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Discussion Starter · #1 ·
So I just got an OBDLink MX and AlfaOBD. I checked for codes in the OBDLinkapp, and it came back with U0140. I haven't had CEL in years and everything with the car seems to be ok, so I'm wondering if I should clear this and see if it comes back. I tried looking with AlfaOBD under the BCM but no codes are thrown. If I clear the code using OBDLink app, it says my car will run poorly for a short time cuz it's resetting a bunch of stuff.

Any thoughts or ideas?
127633

127634
 

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It is a standard diagnostic procedure to clear any codes to see if they reappear.
 

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Discussion Starter · #3 ·
I'm worried about the bad performance and how long it'll last. Guess I'll give it a whirl.
 

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It's a network code, you won't notice anything.
 

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Discussion Starter · #5 ·
Hey thanks for helping.

So, It didn't get cleared. OBDLink App asked what to clear, I selected all, then it re read them. Tried twice. The code isn't listed in AlfaOBD under Body Computer or Engine.
 

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It may be a glitch in their software. There are other apps like Torque that work with any scanner. Try that and report back.
Leaving the negative battery terminal disconnected for a while can also clear codes. Do not remove the nut on the negative battery terminal, just loosen it and then remove the cable from the battery.
 

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Discussion Starter · #7 ·
No codes in Torque, gonna unhook the battery next and get back to ya.

I did find this while researching the code:
127636


No lights on the dash tho. 😕
 

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There are 3 types of DTCs. The same DTC can be reported in more than 1 category during a diagnostic scan.

"Pending" DTCs are codes where there is a fault condition that is approaching the requirements of setting an active DTC. For example, if a cylinder starts misfiring, it will need to misfire a certain number of times in a time period before setting an active misfire fault code and triggering the CEL, but it will show up on a scan as a pending code if that condition hasn't been met yet. You may never get an active code, and pending DTCs don't trigger the CEL.

"Active" DTCs are codes where the conditions have been met to trigger a fault. Most active codes will trigger a CEL, and some will activate a secondary warning light. For example, an active ABS-related code would trigger the CEL as well as the ABS light. The first step to confirming that the issue is real (assuming it isn't obvious from the vehicle's performance) is to clear the code and see if it returns.

"Permanent" DTCs are codes where the condition was previously set and cleared, but a historical record is kept for diagnostic purposes. Permanent DTCs cannot be erased by normal means, and this is by design. Permanent DTCs do not indicate an existing fault condition, and as such will not trigger a CEL.

In your case, at one point you had a U0140 code active because some module lost contact with the BCM. It may or may not have triggered a CEL (some codes don't, especially U codes, which are for network issues), but whatever the problem was, it was likely cleared quickly by the module either re-attempting the connection successfully, or by turning off and restarting the car. The modules in modern cars are sophisticated computers that communicate with each other over a network. If you have any experience with computers and networks, you know that sometimes things just stop working or responding and are often easily fixed by rebooting them. Today's cars are not so different.
 

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Discussion Starter · #9 ·
Ok cool. Thanks for the info. I had a pedal voltage CEL trigger a few years ago and a buddy cleared it for me. The stats at one point said I had 880 some startups since last cleared, so two starts a day, yea, a few years ago. 🙃

Didn't get a chance to do the negative battery cable, but it's not gonna clear anyway. I'll see if any pending codes come up. AlfaOBD apparently doesn't read permanent codes. 😕
 

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Ok cool. Thanks for the info. I had a pedal voltage CEL trigger a few years ago and a buddy cleared it for me. The stats at one point said I had 880 some startups since last cleared, so two starts a day, yea, a few years ago. 🙃

Didn't get a chance to do the negative battery cable, but it's not gonna clear anyway. I'll see if any pending codes come up. AlfaOBD apparently doesn't read permanent codes. 😕
Here is the thing? This error happens often in any network as packet collisions occur. I have noticed in my healthy Dart, I see them pop through specially when I am in diagnostic mode. It seems the official diagnostic reader/programmer is intrusive and bangs the CAN network causing these errors. Having said that if you have a service engine or system light on while you drive it and it does not go away, you may have a differential CAN wire that has been pinched or has gotten corroded some where, In this case, If I can I would go to each module, identify the com wires and clean the pins after checking for continuity if I could. This condition is rare and something drastic would have had to happen, as in the car was wrecked, flooded. Someone messed with the wiring to affect full contact. About 60 miles, they all should complete. Pull the OBD2 reader off the system and go in to check when they are completed, If the body is still left, I suggest you roll up your sleeves and get to work.
 

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I just thought about this and it is very important, something I posted last year. When the battery is marginal, in this car, or any newer cars, we start to experience Twilight Zone OBD2 errors. If you know that I mean. There is nothing wrong with car, I went for a better and higher amperage battery and all of my errors went away. I do have the limited and that one is fully loaded with a dual clutch transmission and those little actuators need good enough current but after the transmission gets pressurized it leaves the battery a little weak and the fun begins.

Get a yellow battery from Autozone, don't turn the core in and if that is not the problem, take it back and get your money back into your pocket.

Ed
 
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