CL-Fault: 5.7 Vortec

[east302]

I hate to sound like an idiot, but this is the first time I've ever heard of "CL-Fault".

Is that specific to the scan tool you're using? Or is it a legitimate factory-specified deal?

I was wondering that, too. Is CL-Fault something reported by a Tech2 or is it something that a scanner is reporting by interpreting something else (that “something else” then triggering a DTC so that you’d know what may be causing the fault)?


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[suredoes]

Check out my first post in this thread. That’s as much of the issue as I understand. The part of this that’s really getting me is both bank being faulted at same time. This isn’t something I’ve seen before.

it is reported by a scanner, I mentioned the model somewhere in here but just regular scanner.

there are no DTC/CEL which also makes this tough. If I wasn’t looking at the tool I would think the truck was fine. It drives well...so that’s what sparked the original question from first list of is this normal.

I plug in the scan tool and start up the truck. Coolant temp read under 100°f like ambient temps currently. It quickly starts climbing as the truck sits and more so if driving of course.

At this time the scan tool live data(that shows me coolant temp) says ‘OL’ open loop. Then around 120-140°f it changes to clfault.

in any other vehicle this goes to CL as it should.

PCM/ECU used open loop to warm up cars, like putting the choke on a mower. At certain coolant temp switch to closed loop to best refine the air fuel mixture based of sensor fedback and engine operating parameters. I am not sure what a 2 bank fault means..so that’s why I’m here!

the PCM doesn’t like something. But from what I can see an feel In how the truck drives plus what I can see and have understanding of from live data in tool things look ok. Need to get IR thermometer on the cats to better see if they are working.

If anybody has a obdii truck and wants to plug in a scanner and see if it says what mine says that would be helpful. More data points.

 

[stutaeng]

I'm guessing the CL-Fault deal makes it run the same as if in Open Loop? You'd think the fuel economy takes a dive?

In other words, the ECU is not using the O2 sensor data for fuel management? But that's not consistent if OP mentioned the fuel trims look good. That's puzzling.

 

[suredoes]

I'm guessing the CL-Fault deal makes it run the same as if in Open Loop? You'd think the fuel economy takes a dive?

In other words, the ECU is not using the O2 sensor data for fuel management? But that's not consistent if OP mentioned the fuel trims look good. That's puzzling.

this is about here my knowledge drops off. I do know when you have a single bank fault it just replicates the known good bank o2 readings and fuel trims into the bad bank. But that’s not what I have, I have both in fault mode.

Fuel trims on the two banks aren’t identical so seems like they operate independently?

it may run a bit rich but not dumping fuel pig rich. I don’t drive the truck much so fuel economy is hard to pinpoint. Only use it for Home Depot runs and such.

 

[Schurkey]

Use the scan tool to clear codes, see what happens.

 

[suredoes]

I don’t have codes since I cleared the one for upstream o2. Cleared code and put new o2..both banks. No codes since probably 100 miles of driving.

edit: CL-fault isn’t a code, it’s the status of the PCM. It just tells you what ‘mode’ it’s in. When the coolant temp comes down back to open loop it goes. Vehicles start in open loop and run there for a second, if warm, as well.

 

[Schurkey]

If you clear the codes AGAIN, then run the engine, I'd hope you go from open-loop to closed-loop without have a CL-Fault. At least until the computer figures out something is wrong. Then maybe the CL-fault reappears.

There's different kinds of codes--can your scan tool read them all?
Current codes
History codes
Pending codes

 

[suredoes]

I will triple check, but pretty sure when I ‘erase codes’ it says ‘no codes present’.

I can see stored and pending, nothing in pending. Don’t think I’ve got a history option.

 

[suredoes]

Well I think I got an answer..and can’t believe I’ve been chasing my tail like this.

bank 1 cat seems bad. Infrared thermometer gave me the final clue.

I guess the way this system operates both banks show as fault? Not sure what I’ll do you. I have inspections here and no CEL for now..cats are $$$. Maybe this will help someone in the future.

thanks for all the Input.

 

[stutaeng]

Well I think I got an answer..and can’t believe I’ve been chasing my tail like this.

bank 1 cat seems bad. Infrared thermometer gave me the final clue.

I guess the way this system operates both banks show as fault? Not sure what I’ll do you. I have inspections here and no CEL for now..cats are $$$. Maybe this will help someone in the future.

thanks for all the Input.

Thanks for the update and diagnostics. What are you seeing as far as temperature in the faulty vs the good cat?

I'm wondering why a CEL was not thrown for the faulty Cat?

I'd try to find some junkyard ones and run them. Some areas may be hard to do that because of the high theft rates.