Can not clear CEL Check engine light ?


jaxgt

GT Owner
Mark IV Lifetime
Jul 12, 2006
2,795
New battery going in this am. Fingers crossed. Will update. Thanks!
 
  • Like
Reactions: 2112

jaxgt

GT Owner
Mark IV Lifetime
Jul 12, 2006
2,795
Update - just put new Optima battery in. As of now, CEL is OFF!!! No idea why or what was issue, as the old battery is putting out 12v on tester and otherwise appeared to work fine. Will run it some this wkend with the new battery to confirm CEL stays off.
 
Last edited:

twobjshelbys

GT Owner
Jul 26, 2010
6,062
Las Vegas, NV
Update - just put new Optima battery in. As of now, CEL is OFF!!! No idea why or what was issue, as the old battery is putting out 12v on tester and otherwise appeared to work fine. Will run it some this wkend with the new battery to confirm CEL stays off.
Yep. The electronics are sensitive...

Note: You'll have to run the drive cycle to get the emissions readiness tests run...
 

GT@50

GT Owner
Mark II Lifetime
Dec 14, 2019
866
Issaquah
Wow. I wonder if a factory scan tool would have pulled a code.
 

jaxgt

GT Owner
Mark IV Lifetime
Jul 12, 2006
2,795
No idea. I have two diff code readers (that I have used many times without a problem) that didn't read a code. One was my handheld sct tuner and another gizmo.
 

HNS

GT Owner
Mar 11, 2020
98
East Coast
Update - just put new Optima battery in. As of now, CEL is OFF!!! No idea why or what was issue, as the old battery is putting out 12v on tester and otherwise appeared to work fine. Will run it some this wkend with the new battery to confirm CEL stays off.
Thanks for the update!!
 

twobjshelbys

GT Owner
Jul 26, 2010
6,062
Las Vegas, NV
Wow. I wonder if a factory scan tool would have pulled a code.
not after disconnecting the battery
 

extrap

GT Owner
Mark II Lifetime
Jul 16, 2020
1,768
Gainesville FL
Update - just put new Optima battery in. As of now, CEL is OFF!!! No idea why or what was issue, as the old battery is putting out 12v on tester and otherwise appeared to work fine. Will run it some this wkend with the new battery to confirm CEL stays off.
(y) :cool: (y) :cool: (y)
 

PL510*Jeff

Well-known member
Mark IV Lifetime
Le Mans 2010 Supporter
Nov 3, 2005
4,881
Renton, Washington
Good that things seem OK. A while back I took my GT in to my Ford dealer. I had intermittent issues with starting. The ran a 2 hour test of the battery, as alternator was operating as designed and battery was showing full charge, and yes I needed a new battery. I had them run same test on my Fusion hybrid as it had intermittent issues too. Same test and yes it needed a new battery. In talking to my service tech about his he said 1) in the garage don't keep the keys "within range" and 2) when parking for a longer time, in a secure garage, leave the alarm off. Otherwise the electronics will hunt actively for the connection and continuously draw down the battery.
 

dreimer

GT Owner
Mark II Lifetime
Feb 8, 2018
169
Ponte Vedra Beach, FL
When the yellow TPMS light went on in my wife's Honda Odyssey minivan in 2011, I fixed it by covering it with a yellow post-it note. ;) We just traded it in last month after 11 years and 220,000 miles. All with the post-it note on the dashboard.:LOL:

Probably not the best solution for your case though. Seriously though, I hope it goes away or you figure it out.
 
  • Like
Reactions: viva gt

twobjshelbys

GT Owner
Jul 26, 2010
6,062
Las Vegas, NV
When the yellow TPMS light went on in my wife's Honda Odyssey minivan in 2011, I fixed it by covering it with a yellow post-it note. ;) We just traded it in last month after 11 years and 220,000 miles. All with the post-it note on the dashboard.:LOL:

Probably not the best solution for your case though. Seriously though, I hope it goes away or you figure it out.
Unfortunately for those of us that have emissions testing that strategy will not work. As more emissions tests move to the OBDII based tests, the first check is that the "presence of the Check Engine Light is an automatic failure". It doesn't matter if there are no codes... The tech won't even look further.

TPMS is a boatload too. Our Honda CRV hit a pot hole and the TPMS light came on and I'd reset it and sometimes it would come back and sometimes it would stay off until I'd hit another bump... Unfortunately Honda's system doesn't tell you WHICH sensor is triggering so until I get new tires I'll live with it.

(PS, it's gone, new battery - keep reading which you will probably have done by the time you see this :) )
 

twobjshelbys

GT Owner
Jul 26, 2010
6,062
Las Vegas, NV
Good that things seem OK. A while back I took my GT in to my Ford dealer. I had intermittent issues with starting. The ran a 2 hour test of the battery, as alternator was operating as designed and battery was showing full charge, and yes I needed a new battery. I had them run same test on my Fusion hybrid as it had intermittent issues too. Same test and yes it needed a new battery. In talking to my service tech about his he said 1) in the garage don't keep the keys "within range" and 2) when parking for a longer time, in a secure garage, leave the alarm off. Otherwise the electronics will hunt actively for the connection and continuously draw down the battery.

Similar issue in my Dodge Ram pickup. I added a self-dimming mirror with Homelink. My garage door opener died and when I re-trained it to the mirror it worked. Then it stopped. I'd also noticed recently that when I turn on the key that the battery indicator doesn' get to the normal position until the engine is started (alternator kicks in). I threw it on the trickle charger for a couple of days (my old high power battery charger bought the farm) and when it switched to charging to charged the garage opener worked again. Battery is close to end of 3 year warranty which is at the high end of battery life here in Vegas.
 

extrap

GT Owner
Mark II Lifetime
Jul 16, 2020
1,768
Gainesville FL
When the yellow TPMS light went on in my wife's Honda Odyssey minivan in 2011, I fixed it by covering it with a yellow post-it note. ;)
Ha! (y) I've been know to use a paper hole punch on a piece of black electrical tape and pop that little round sticker over a silly check engine light! 😃

The check engine light has been on in my 2005 Nissan Titan for about 80k miles. Mechanic told me he could fix it easy, so I paid him, and the light was out!

... until I was just about back to my driveway 😠
 

GT@50

GT Owner
Mark II Lifetime
Dec 14, 2019
866
Issaquah
Black electrical tape was the solution to every K car out there.
 

PeteK

GT Owner
Mark II Lifetime
Apr 18, 2014
2,291
Kalama, Free part of WA State
My 2-1/2 y/o optima works fine if I am driving every day or have it on my smart charger.

If it sits for a week without the smart charger, it can’t start the car. Replacing it this spring.

Moral to my story? These batteries can fool you into thinking they are ok.

Plus, subscribing to learn what your solution is.
Mike, that's odd. I have an Optima in my car, about 2.2 years old, I hadn't driven my car for about a month, and I was concerned that the parasitic drains might have depleted it, but it started right up. Us WA-Staters should get together for a garage session sometime soon.
 

Tomcat

GT Owner
Black electrical tape was the solution to every K car out there.
We also carried it in the TomCat (for those pesky warning lights during night carrier landings).
 

jaxgt

GT Owner
Mark IV Lifetime
Jul 12, 2006
2,795
Drove 15 mi today after installing new optima. Still no CEL !!!
 

HighHP

GT Owner
Jun 3, 2019
437
Spokane, WA
That makes no sense if both batteries put out the same voltage. Maybe, put the old one back in to see if it really is the battery. 😁
 
  • Like
Reactions: dreimer

SYCO GT

GT Owner
Mark II Lifetime
Sep 9, 2006
4,975
California
Yes I have seen batteries occasionally pass a test, and appear fully charged/chargeable - but in reality not performing appropriately. When in doubt, and particularly for a battery that is more than 3.5 years or so, it's often worth it to replace it.
 
  • Like
Reactions: jaxgt

Howard

GT Owner
Mark IV Lifetime
Apr 26, 2007
1,136
Florida/North Jersey
I wonder if the battery exchange process improved the ground connection at the battery or the chassis.