• Mustang Forums
  • Digital Self-tuning Forum

MegaSquirt CEL popped on?

  • Thread starter Thread starter afjLX
  • Start date Start date Dec 29, 2024
  • 1
  • 2
Next
1 of 2 Next Last
A

afjLX

Member
Nov 16, 2024
83
20
18
DFW,TX
Dec 29, 2024
#1
  • Dec 29, 2024
  • #1
So something weird occurred this morning when I started the car. The Check Engine Light came on and stayed on. So would the MS trigger a CEL? I didn’t think it would??
Is there a way to look up sensors to see if I have an issue all of a sudden?

I’m using the MegaSquirt V2 for Fox Mustangs.
 

AeroCoupe

lube between the nut and the face. I know my lubes
Founding Member
Oct 28, 2001
6,114
4,212
183
Claremore, OK
Dec 29, 2024
#2
  • Dec 29, 2024
  • #2
From my understanding it will not. I have never seen this but thought it was worth mentioning in the rare case the previous owner did this to pass emissions:

Installing MegaSquirt in Parallel With the Stock ECU

While there are many cars where MegaSquirt can completely replace the stock ECU, on some cars you’ll need to leave the stock ECU in place. There’s several reasons why you might want to do this. On some installations, you might want to have the MegaSquirt control just the fuel and would rather...
www.diyautotune.com

From what I have read most states that still do emissions checks on the 95 and down cars only look for the CEL to come on when the key is put in the run position and then to go out in 3-5 seconds. Would be easier to wire it to a timer than to parallel the two ECU’s.
 

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor
Admin Dude
Jan 4, 1985
43,353
21,554
234
Box behind Walmart
Dec 29, 2024
#3
  • Dec 29, 2024
  • #3
This is why progress threads are so handy.

A Progress Thread contains [all] the ailments of your car in one thread.

This and some of the issues in your other threads may be related.
 
Reactions: nickyb

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,311
18,025
224
Massachusetts
Jan 3, 2025
#4
  • Jan 3, 2025
  • #4
Yes, you can enable a CEL with Tuner studio that will trigger the check engine light. It doesn't quite work like a normal check engine light.

The menu for it is under "Canbus/Test Modes"

Under "Light output" you can see what pin on the MS it's wired to the output of.



As you can see, what you are really doing is setting MAX/MIN specs for various sensors. If it ventures outside that range, it will trigger a CEL.
 
Last edited: Jan 3, 2025
A

afjLX

Member
Nov 16, 2024
83
20
18
DFW,TX
Jan 3, 2025
#5
  • Jan 3, 2025
  • #5
Mustang5L5 said:
Yes, you can enable a CEL with Tuner studio that will trigger the check engine light. It doesn't quite work like a normal check engine light.

The menu for it is under "Canbus/Test Modes"

Under "Light output" you can see what pin on the MS it's wired to the output of.



As you can see, what you are really doing is setting MAX/MIN specs for various sensors. If it ventures outside that range, it will trigger a CEL.
Click to expand...

Thank you!! I will check it today!
 

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor
Admin Dude
Jan 4, 1985
43,353
21,554
234
Box behind Walmart
Jan 3, 2025
#6
  • Jan 3, 2025
  • #6
So, you can set your own. That's pretty nice.
 
A

afjLX

Member
Nov 16, 2024
83
20
18
DFW,TX
Jan 3, 2025
#7
  • Jan 3, 2025
  • #7
Mustang5L5 said:
Yes, you can enable a CEL with Tuner studio that will trigger the check engine light. It doesn't quite work like a normal check engine light.

The menu for it is under "Canbus/Test Modes"

Under "Light output" you can see what pin on the MS it's wired to the output of.



As you can see, what you are really doing is setting MAX/MIN specs for various sensors. If it ventures outside that range, it will trigger a CEL.
Click to expand...
Well, I’m unable to find anything in tuner studios for light output or check engine light under canbus. I’m using a MegaSquirt gen2.
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,311
18,025
224
Massachusetts
Jan 3, 2025
#8
  • Jan 3, 2025
  • #8
Which version of TS are you on?


Is this the ECU you have?

AMP Plug-and-Play ECU - Ford 1986-1993 Foxbody Mustang 5.0

The NEW full standalone AMP Play-N-Play ECU for the 1986-1993 Ford Mustang 5.0 and 1986-1988 Thunderbird 5.0, installs in under 1 hour.
www.diyautotune.com
 
A

afjLX

Member
Nov 16, 2024
83
20
18
DFW,TX
Jan 3, 2025
#9
  • Jan 3, 2025
  • #9
Mustang5L5 said:
Which version of TS are you on?


Is this the ECU you have?

AMP Plug-and-Play ECU - Ford 1986-1993 Foxbody Mustang 5.0

The NEW full standalone AMP Play-N-Play ECU for the 1986-1993 Ford Mustang 5.0 and 1986-1988 Thunderbird 5.0, installs in under 1 hour.
www.diyautotune.com
Click to expand...

Yep that’s the one I’m running. I’m using TunerStudio MS Ultra v3.2.05
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,311
18,025
224
Massachusetts
Jan 4, 2025
#10
  • Jan 4, 2025
  • #10
afjLX said:
Yep that’s the one I’m running. I’m using TunerStudio MS Ultra v3.2.05
Click to expand...

Let me dig around a bit. Did you do the initial setup and tune?
 
A

afjLX

Member
Nov 16, 2024
83
20
18
DFW,TX
Jan 4, 2025
#11
  • Jan 4, 2025
  • #11
Mustang5L5 said:
Let me dig around a bit. Did you do the initial setup and tune?
Click to expand...
Yep, sure did.
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,311
18,025
224
Massachusetts
Jan 6, 2025
#12
  • Jan 6, 2025
  • #12
SO you do not have this menu under this header at all?

 
A

afjLX

Member
Nov 16, 2024
83
20
18
DFW,TX
Jan 7, 2025
#13
  • Jan 7, 2025
  • #13
Mustang5L5 said:
SO you do not have this menu under this header at all?

Click to expand...
I have that pulldown but the check engine light option is not there.
 

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor
Admin Dude
Jan 4, 1985
43,353
21,554
234
Box behind Walmart
Jan 7, 2025
#14
  • Jan 7, 2025
  • #14
There must be a switch somewhere


 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,311
18,025
224
Massachusetts
Jan 7, 2025
#15
  • Jan 7, 2025
  • #15
I'm on TS MS Lite v3.2.05 and it's there. Not sure why it would be missing from yours.
 

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor
Admin Dude
Jan 4, 1985
43,353
21,554
234
Box behind Walmart
Jan 7, 2025
#16
  • Jan 7, 2025
  • #16
Mustang5L5 said:
I'm on TS MS Lite v3.2.05 and it's there. Not sure why it would be missing from yours.
Click to expand...

Is there a way to enable/disable the option, by chance?
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,311
18,025
224
Massachusetts
Jan 7, 2025
#17
  • Jan 7, 2025
  • #17
Noobz347 said:
Is there a way to enable/disable the option, by chance?
Click to expand...

You can turn it on/off but it’s within that particular menu itself.
 

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor
Admin Dude
Jan 4, 1985
43,353
21,554
234
Box behind Walmart
Jan 7, 2025
#18
  • Jan 7, 2025
  • #18
Check this for Esses and Geez:

If you don't see the Check Engine Light option:

  • Ensure Advanced Menus Are Enabled:
    • Go to Options > Preferences.
    • Set the interface level to Advanced.
 
A

afjLX

Member
Nov 16, 2024
83
20
18
DFW,TX
Jan 7, 2025
#19
  • Jan 7, 2025
  • #19
Noobz347 said:
Check this for Esses and Geez:

If you don't see the Check Engine Light option:

  • Ensure Advanced Menus Are Enabled:
    • Go to Options > Preferences.
    • Set the interface level to Advanced.
Click to expand...

I will try that when I get home tomorrow. Will report back then.
 

Gibson17

Member
Oct 25, 2000
7
4
13
Masshole
Jan 12, 2025
#20
  • Jan 12, 2025
  • #20
I too am interested in this. I have the MSPNP2 in my foxbody and MS Ultra v3.2.05 and under options>preferences there is no Advanced Menu eneable option.
 
  • 1
  • 2
Next
1 of 2 Next Last
You must log in or register to reply here.

Similar threads

M
Best way to find out wheres ground flows?
  • martroy
  • Jun 30, 2025
  • Digital Self-tuning Forum
Replies
3
Views
244
Digital Self-tuning Forum Jul 4, 2025
martroy
M
P
Weird Voltage & Oil Pressure Gauges
  • PNN
  • May 22, 2026
  • SN95 V6 Mustang Tech
Replies
0
Views
109
SN95 V6 Mustang Tech May 22, 2026
PNN
P
Electrical Code 29 again
  • Creomod
  • Jul 31, 2026
  • Fox 5.0 Mustang Tech
Replies
7
Views
270
Fox 5.0 Mustang Tech Aug 3, 2026
Creomod
E
2007 GT Stalls when lights or a/c turned on
  • ejscarfo
  • Jun 22, 2026
  • 2005 - 2009 Specific Tech
Replies
2
Views
214
2005 - 2009 Specific Tech Jun 29, 2026
ejscarfo
E
F
Fox 1990 Mustang GT 5.0 A9L – Engine suddenly shuts off but immediately restarts when key turned
  • FishermansFriend
  • Aug 9, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
16
Views
509
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Aug 30, 2026
General karthief
Share:
Bluesky Email Share Link
  • Mustang Forums
  • Digital Self-tuning Forum
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?