Is it Possible to disable CEL?

[cornflakes2]

I'm just wondering, is it possible (I'm sure it is as anything is possible) or maybe is it common for a shady person/business
to somehow disable the CEL in a car's ECU so as to make it look like there is nothing wrong with a car? Or do all cars must have it working
and/or it's very difficult to hack into it and disable CEL to cover up deep problems they don't want you to know about (ie. a used seller/dealer for example).

[OldGermanHeaps]

Its easy either to cut the track in the cluster and connect the cel to the airbag light or alternator or abs light to make it appear to work properly, its also only £30 to have a custom remap written that deletes individual fault codes so it wont register even with diagnostic gear, it just sets the trigger parameters out of range..

[98elise]

I suspect custom maps are going to be popular given the recent MOT changes.

[edc]

Much easier to just check and clear the code before a test drive. Most codes won't trigger the light again until a couple of ignition cycles.

[cornflakes2]

now "IF" someone did this to a car to prevent finding fault codes or serious issues, is this sort of thing not against the law or criminally liable?
Are people allowed to do this and get away with it? I'm just asking because I honestly don't know how it works (both in the automotive industry and the actual 'how to' of remapping the ECU so no fault codes show up).

Let's say that I have a car that I find out has major issues and I want to resell it and I ask a garage to remap my ECU so that it will basically show up fault free. Is that allowed? Could there be any kind of legal action taken if discovered?

[havoc]

[makes note never to buy car from cornflakes]

[jkh112]

Last week you were saying your car does not show any fault codes or a CEL warning even though it does not run smoothly.
On a different thread you indicate you have a missing or damaged aftermarket air filter element and now you have started another thread asking about disabling the CEL warning.
Do you now have a CEL warning?

[cornflakes2]

Sorry, yes I have a gazillion questions because I am just learning about cars and engine parts for the first time and I think I've self-studied myself from complete newb to foundational basics of car mechanics all in just 2 or 3 weeks with no training or education...just self-learning from the good ol internet,
thanks to sites like Chris Fix, Eric the Car guy, ShopDap, humblemechanic, etc....I'm self-crash coursing as much as I can. I could probably DIY a lot of these things now but I just don't have the tools and experience so afraid to try and fix things myself.

No CEL on my car, EVER while I have owned the car. Even when it shut off by itself. No fault codes found by me on my cheap OBD2 reader and none found at 3 garages I went to. Two of them were tuning garages specific to my car and model and the other garage was an actual VW service center. Nobody found any fault codes or told me about any fault codes.

• i must make this note, a couple months ago while driving, my car suddenly lost power at the pedal and it sputtered out after 1 minute later I had no power...even at that time no CEL came on. Now I dunno if it's just me, but, don't you think if a car engine just loses power to the point of sputtering dead, that that should trigger a CEL or fault code of some kind? Yet none** The only light that ever came on now that I recall was a tire pressure light. I put more air in the tires and reset the tire check light and it never came back on so that at least that seems to be working.

I did get a print out of the service history of my car and it appears that the previous owner had 1 or 2 fault codes show up but they didn't specify which codes they were. I only see a small note beside the date and location of where the car was for servicing. One of the notes says a check bulb light came on (which I'm assuming meant CEL) and another said transmission event appeared (dunno what that means), but those were all like last year before I bought the car. From the day I owned it back in November 2017, there have been no CEL or no fault codes.

So I'm just wondering a lot now.

Edited by cornflakes2 on Saturday 17th March 16:44

Edited by cornflakes2 on Saturday 17th March 16:47

[jkh112]

Check bulb more likely to mean check your bulbs as one of them has blown (meaning headlight or tail light bulb).
It is quite normal for a car to have some codes recorded in the past which have now been sorted and therefore cleared. The issue is if they keep coming back.

[fooby]

What car is it? A family member of mine with a 2014 Mercedes Citan has what sounds like a similar issue. No CEL or fault codes but it'll throw up random things like blown bulbs when there's nothing wrong and sometimes won't start at all. Does it have any aftermarket wiring? Head units, reversing sensors etc? His problems started after installing a reversing camera. Not sure if it's something to do with CAN bus, but might be worth looking into

Also your spluttering / cut off issues could be a dirty throttle body or an injector issue. What caused this issue on my Micra was a stretched timing chain.

[stevieturbo]

cornflakes2 said:

No CEL on my car, EVER while I have owned the car.

Clearly, key on, engine off the light should be on.

if it isnt then either the bulb is not working, or as you allude to...someone has removed the bulb. Or least likely someone has disabled it in the ecu.

Of course it is very very common for people to delete faults via the ecu so the light does not come on, often unscrupulous car sellers/dealers who need to get rid of a problematic car.
Or it can simply be one of the dodgy remapper types out there. But even in those cases key on, engine off the light should still light up.

[Arif110]

I was under the impression that (an orange) Check Engine Light actually relates only to 'emissions' issues. So say your EGR valve plays up, the CEL & traction control lights will come on, as the engine considers the EGR a necessary part of the 'engine control' equation.

[stevieturbo]

CEL can light up for a wide range of issues.

If it doesnt light up at all...that's a bigger issue lol

[cornflakes2]

sorry for the confusion. All the lights turn on with key on, engine off (including CEL), but I meant that the CEL never turned on while driving, even when the car sputtered out that one time, there was no CEL and now when the car can't stay on after startup during idle, no CEL.

Yes, we checked throttle body and it was super clean. I'll have to find out if someone can check the fuel injectors as that seems to be next on my hit list to check out. I haven't been able to do anything yet since I discovered my air filter was half gone so I don't want to drive it any more until I get my new air filter which I ordered already. It should be here by next week. After I install it myself, I'll take it down to another APR authorized dealer that I found and see if they can do a check up on my ECU mapping.

[Krikkit]

We'd need to know more about the car, but that doesn't sound unusual. Some just aren't sophisticated enough to recognise their own faults.

[cornflakes2]

2013 Scirocco R, with APR Stage 2+, 55k km.
I don't personally believe that anything was intentionally concealed or kept hidden by manipulating the fault codes or CEL thresholds but of course, I could be wrong. But it's just a thought I had because I tend to think about things like that, the "What ifs?"

I also have another question but seems like I've been asking too many questions, I'm not allowed to post anymore new threads so I'll just ask here and hope enough eyes see this to give some answers.

As I've been self-studying, I've come across a lot of confusing terms and the reason is because I found out many parts/tools go two or more names! It's really confusing for a newbie when studying/researching. It would help if any of the more experienced mechanics here could point out some more tools/parts that often go by two or more different names.

Here are a couple that confused the hell out of me until I realized they are actually the same thing, just different names!

-allen keys are the same hex keys
-cam follower is the same also known as the fuel pump tappet (WTH?)
-coils/coil overs are all the same things as ignition coils or coil packs ---> they all mean the same thing!!
(previously some people were telling me to change coil packs and then another was saying change ignition coils and I was like....wth? only to find out later they are actually the same thing).

any others you can let me know of? thanks

[stinkyspanner]

Erm, I think you might need to get your books back out.. Sorry

[Defcon5]

How have you established that coilovers are the same as ignition coils?

[E-bmw]

cornflakes2 said:

-allen keys are the same hex keys
-cam follower is the same also known as the fuel pump tappet
-coils/coil overs are all the same things as ignition coils or coil packs

Allen is a brand name manufacturer of hex keys that has become the norm, just like most people call a vacuum cleaner a Hoover, which is a brand name.

A cam follower is often colloquially called a tappet like an automobile is often colloquially called a car.

Coils aren't the same as coilovers, coilovers are suspension, coils are more correctly called ignition coils, coil packs are a more modern version commonly found on cars now.

[MB140]

Doesn’t have one of these oil type air filters does it. I know the oil on the air filter can fk up the MAF and cause spurious engine running issues.