Confess if you drive around with your CEL on

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Originally Posted By: TinyVoices


Yep. That was me as embarrassing as it is to admit. This was back in the early 2010s and the car was slammed on cheap coilovers and sitting on wheels worth 1/2 the value of the car. It was so low I could push small gravel around with the lip and the exhaust touched the ground on flat roads.

Yaknow, I think the check engine light is a lot less embarrassing than the rest of that car. Looks to me like it rode like a pregnant rollerskate, haha.
 
Originally Posted By: Nick1994
Yup, I added an auxiliary switch to the electric fan on my Jeep. If I turn the switch on, the CEL comes on for "open fan circuit" but when I turn the switch off, later that day the CEL goes away.

Doesn't bother me. When it's due for emissions I just won't turn the fan switch on for a couple days (it comes on automatically too).

But what's the point of manually controlling that fan if it normally comes on when intended? Just for your peace of mind in that AZ heat?
 
Only when I can't fix it ASAP.

01 Tundra P0420, stopped using Lucas UCL in the gas and code did not come back after a couple fill ups.
02 Silverado P0332, drove it like that until parts arrived from Amazon and fixed the issue in a weekend.
04 Ford F250 company truck, P0306, huge POS so I just changed out just the cyl6 plug.
 
Originally Posted By: Kibitoshin
Only when I can't fix it ASAP.

01 Tundra P0420, stopped using Lucas UCL in the gas and code did not come back after a couple fill ups.
Confirmed for cat poison!!
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Originally Posted By: L_Sludger
Originally Posted By: Nick1994
Yup, I added an auxiliary switch to the electric fan on my Jeep. If I turn the switch on, the CEL comes on for "open fan circuit" but when I turn the switch off, later that day the CEL goes away.

Doesn't bother me. When it's due for emissions I just won't turn the fan switch on for a couple days (it comes on automatically too).

But what's the point of manually controlling that fan if it normally comes on when intended? Just for your peace of mind in that AZ heat?
The fan comes on at too high of a temp IMO, I'd like to turn it on while out off-roading in the desert and sand and leave it on to prevent those high temperatures.

Turning the A/C on also turns the fan on, but it cycles. Sometimes I want the fan on in the desert with no a/c as well

Originally Posted By: Colt45ws
Originally Posted By: Nick1994
Yup, I added an auxiliary switch to the electric fan on my Jeep. If I turn the switch on, the CEL comes on for "open fan circuit" but when I turn the switch off, later that day the CEL goes away.

Doesn't bother me. When it's due for emissions I just won't turn the fan switch on for a couple days (it comes on automatically too).

If you are tapped into the fan relay and triggering it that way, you can add a diode between the pcm and where you are tapping off. Then it wont see you closing the relay.
Wow, thanks! I'll have to look into how to wire that in
 
Originally Posted By: Nick1994
Originally Posted By: L_Sludger
Originally Posted By: Nick1994
Yup, I added an auxiliary switch to the electric fan on my Jeep. If I turn the switch on, the CEL comes on for "open fan circuit" but when I turn the switch off, later that day the CEL goes away.

Doesn't bother me. When it's due for emissions I just won't turn the fan switch on for a couple days (it comes on automatically too).

But what's the point of manually controlling that fan if it normally comes on when intended? Just for your peace of mind in that AZ heat?
The fan comes on at too high of a temp IMO, I'd like to turn it on while out off-roading in the desert and sand and leave it on to prevent those high temperatures.

Turning the A/C on also turns the fan on, but it cycles. Sometimes I want the fan on in the desert with no a/c as well

Originally Posted By: Colt45ws
Originally Posted By: Nick1994
Yup, I added an auxiliary switch to the electric fan on my Jeep. If I turn the switch on, the CEL comes on for "open fan circuit" but when I turn the switch off, later that day the CEL goes away.

Doesn't bother me. When it's due for emissions I just won't turn the fan switch on for a couple days (it comes on automatically too).

If you are tapped into the fan relay and triggering it that way, you can add a diode between the pcm and where you are tapping off. Then it wont see you closing the relay.
Wow, thanks! I'll have to look into how to wire that in

Understandable; most vehicles with 190-195 thermostats have the fan set to come on 210-215. Can be really hot espically if you have a in-tank ATF cooler and are doing low speed high load, exactly like off road.

That code is a bit different than the Chevy I modded with a fan switch previously; on that one is was complaining about a short to ground, which was true since I was grounding the relay. Just a diode prevented it from seeing ground through my switch, but still allowed it to ground the relay when my switch was off.

The Jeep must be looking for voltage on the fan relay pin. The around 80 ohm relay would be essentially battery voltage at the PCM pin (might have like a 10k resistor pulling it down) until it turns its transistor on. When you ground it, it does not see any voltage, so it throws a code for open fan relay.

Good news is, I was right about the diode, we will need that. A 1 amp rated one such as a 1N400x type is suitable. But we will also need a resistor. 1k ohm should be low enough to provide voltage to it, and is high enough that a 1/4W one will work at normal vehicle voltages (up to 15V or so).

 
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My mom's old Explorer has a CEL on. Needs a cam sensor, and need to remove the intake manifold to get access to it. No time to fix it right now.
 
My M5 had an intermittent CEL for the evap solenoid for ages, which is buried in the back of the vee of the engine under the plenum.

That's the only vehicle I've ever owned with a CEL I didn't immediately fix.
 
Originally Posted By: Colt45ws



Would you call that circuit ground side switched ?

I'm always wondering about what the guys on YouTube mean when that say "power side switched" or "ground side switched."

And then they say things like "pull up circuit design" or "pull down circuit design" when referring to types of automotive circuits.
 
This thread guilted me into fixing mine!

I had replaced the heater pipes in my 206,000 mile 2001 bmw 530i, which required removing the intake manifold. Long job,, but I got it done. Except for not noticing the broken vacuum line going to the valve on the secondary air pump. Had a CEL for "inadequate air flow".

It's upside down and backwards on the bottom of the intake, impossible to see without a camera - or removing the intake.

After seeing this thread, I got my camera, stuck my arm under the intake for a half hour prying off brittle hose and reconnecting it. I didn't replace the hose... another day I guess.
 
Originally Posted By: WillsYoda
I drive 20 year old vehicles, and NEVER have I left a CEL on for more than it takes me to drive home and plug in my OBDII and figure out the problem. Last time it was a misfire that I diagnosed and fixed (failed spark plug gasket getting oil all over the plug).
Heck, I have a cheap code reader in my truck.
Last time I had a CEL, it was a code P0175, System Too Rich Bank 2 (with a P0172, System To Rich Bank 1, pending).
A 2 minute check found this:




Imagine if I had just ignored it?

I don't see how anyone could drive around with one and do nothing about it. Sure if you know what it is and is nothing major and just waiting till you can fix it, I could see that.
But a light on without knowing what it is and doing nothing about it, crazy (reminds me of Penny in the Big Bang Theory, her car finally dies).
 
The CEL in my 1996 Chrysler Concorde (212K) has been on for years. Had it checked once...read as a "lean cylinder misfire", whatever that is. Cleared the code but it came on again soon after. The 3.5L V6 continues to run fine...so why bother?
 
My OCD side won't let me. Same with oil leaks, burned out bulbs, dirty windshields, etc, etc.....
 
My old rotted 2002 F-150 4.6 developed a physically rotted driver's side precat, it was leaking exhaust. By some miracle it passed NJ emissions testing then set the CEL a week later for lean cylinder bank 1 I believe. It wasn't worth me spending money to fix that as it had other long term structural issues sad to say. I drove it for 3 months with the CEL on and sold it for about double salvage value to a police officer in my wife's department. I explained all the issues with it. If he parts it out it's worth many times what he paid for it, it had only the original 70,000 well cared for miles on it. It was a "victim" of the "NJ vehicle cancer". They've used that highly corrosive salt brine here for the last 10+ years.

Whimsey
 
My 95 F150 has since I got it 4 years ago. Don't need it fixed for inspection.
wink.gif


I tried pulling the code, some shenangians with the positive battery cable and a pin under the hood, and counting flashes of the LED. Code was "80-something" near as I could tell, something MAP or EGR related. The pauses between digits and wholly-formed code numbers are not as cut and dry as one would expect, and fords use 2-digit codes sometimes and 3-digit others. Maybe DPFE if they had them back then. Runs fine, ignoring it.

Wife's old SL1 had an intermittent EVAP code that came and went. I suspected a somewhat poorly sealing solenoid on top of the tank. Ignored that. Now her HHR has the same thing, but with two new solenoids, all nylon lines, plastic gas tank. Takes about 2 weeks to set so I think it's just barely out of spec.
 
No CEL on my vehicles but, wife's Punto have occasional (more often then not) ABS light- it will reset itself after maybe 10 starts. Interestingly it works in the rain and dump weather- when needed lol.

Scanner say is front offside sensor, I'm thinking it is only wiring since it does work sometimes.
New is unavailable from FIAT and it was like 200E so just as well..
 
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Originally Posted By: Merkava_4
Originally Posted By: Colt45ws



Would you call that circuit ground side switched ?

I'm always wondering about what the guys on YouTube mean when that say "power side switched" or "ground side switched."

And then they say things like "pull up circuit design" or "pull down circuit design" when referring to types of automotive circuits.


Yes, thats ground switched.
 
Mustangs has been on for years since I put the exhaust system, van also has light on O2 sensor.
 
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