Question for Mechanics

[Glenn Gates]

Due to lack of funds I've been driving my 2002 Silverado for 4 months with a "service engine soon" light on. Went for a 6 mile drive today and noticed the warning light had vanished????? Any ideas?

 

[Bob Kensill]

I would guess some contamination on an O2 sensor. Run some fuel system cleaner through it. One of the best is Seafoam.

 

[Ray Sametz]

My 2002 Ranger does that when it thinks it needs a oil change, roll the odometer and it goes away. Still change my oil every 3000 to 3500 miles. Retired but still need it to make boat races. ....==={}

 

[chas terrell]

Not enough info to try and trouble shot imo.I have a 2002 tahoe that had a phantom check engine light took it to Advance Auto parts to get a free engine diagnostic scan it pinged a sensor in the intake long story short I had a bad intake gasket which is a know to be a problem for its age hope that this helps.

 

[Hydro Junkie]

Taking it to an auto part store that loans code readers is where I'd start. Find out what the light was trying to tell you and then you will be able to diagnose and fix the problem. My Trans Am has an intermittent CE light that is triggered by the EGR valve. Since I don't drive it much, just not worrying about it for now. One thing to remember is that some vehicles go into "limp mode" when the CE light is on. This kills milage as it just dumps fuel into the engine to keep it running until you can get it fixed

 

[Slideblues]

+1 on the Seafoam or Lucas fuel system cleaner woks well.

Cleaning the O2 sensor wiring connectors with a shot of spray brake cleaner helps.

Mass air flow sensor with crud on it will cause probs, spray for that too just remove air tube and give it a shot.

Auto Zone also offers free check on your under dash data port for error codes.

My 07 GMC had a random engine lite till I replaced the gas cap........

Not a mechanic thou , More like shade tree diagnostic,

Gene

 

[FloridaScaleBoater]

It just amazes me what our vehicles do,,,

I too had a CE light that would come on, stay on,,, sometimes would go away.

Seems the gas mileage was crap while the light was on.

Took it to autozone for the free diagnostic,, it came up as a bad thermostat,, I couldn't fathom that as being the problem????

Took it to the Chevy dealership SRVC Dept,,,,, Guess what. I had them change the T-Stat Light been gone awhile now Go Figure

 

[Samuel Hagan JR]

Those trunks a common to having EVAP codes. Mostly Small and Large EVAP codes.

Also P0171, and P0173 codes for being lean.

If you haven't done anything to it the codes should still be stored in the PCM history,

Find out what the code is.

 

[Chilli]

My 03 Suburban had the dreaded Intake manifold gasket leak a few years back causing a lean condition. The light would come and go but twice the condition was bad enough that the motor would go into reduced power mode which restricts the truck to no more than 30 mph. Before I knew what the problem was, I could hear a leak when the engine was first started up but I thought it was at the exhaust manifold.

 

[HOTWATER]

Due to lack of funds I've been driving my 2002 Silverado for 4 months with a "service engine soon" light on. Went for a 6 mile drive today and noticed the warning light had vanished????? Any ideas?

Same thing last week...and 02 Silverado as well. Light has been off for a few days now, but when I first saw it come on it was about 17° out during the morning startup...engine was warming up rough, almost like it was going to stall out...has been starting/warming up and running fine as of late....??

 

[Glenn Gates]

Thanks, Everyone for the replies. The truck never ran poorley or got bad milage so I didn't see it as a urgent problem. The truck was serviced by the local Chev. dealer last summer- and thanks Ray for the reminder on the oil change. There is also a 'change engine oil light" that comes on in the Silverado when that is due- but the last service they dumped out the Mobile one full synthetic 5-20 wt (with around 1300miles on it) and filled it with penzoil 10-30. Got about 3000 mi on it time to get the truck back on it's regular diet. I'll try the seafoam or Lucas.

Thanks,

Glenn

 

[Joe Warren]

Schindler is the Modern Day Car mechanic on IW. It could be about a 1000 things it is trying to tell you. A OBD II Scanner can tell you most of what likely has the light on unless it is a ABS brake problem Then a dealer with a tech 1 maybe required? the guess is the lazy O2 sensor that was able to clean inself off with a long ride on the highway. Saying that cause it sould be changed every 12000 miles. But most wait till it causes a problem, It can cause a lean or a rich condition, Best thing is to have someone scan it that has the info on that year of truck. You can google the trouble code for that year trk if you can pull it out.

 

[mrgary]

Schindler is the Modern Day Car mechanic on IW. It could be about a 1000 things it is trying to tell you. A OBD II Scanner can tell you most of what likely has the light on unless it is a ABS brake problem Then a dealer with a tech 1 maybe required? the guess is the lazy O2 sensor that was able to clean inself off with a long ride on the highway. Saying that cause it sould be changed every 12000 miles. But most wait till it causes a problem, It can cause a lean or a rich condition, Best thing is to have someone scan it that has the info on that year of truck. You can google the trouble code for that year trk if you can pull it out.

replace the gas cap,,if it is no longer tight,,it will cause the check engine light to come on,,it will also cause the light to go on and go off,,after replacing that and it comes back on,,most dealerships will put there portable checker on,,but it will only tell you whats wrong if the light is on

 

[68Bud]

My 97 F-150 will throw a check engine light after a rough warm up too. Checked it and found out it was a misfire in #3 cylinder. After numerous starts without incident the check engine light goes out. My guess is the engine management computer resets itself after a certain number of good restarts.

 

[Andy Greene]

Until someone pulls a code on this vehicle anyone can toss darts at the several hundred variables that exist here. This thread is like trying to talk someone through flying an aircraft on a keyboard. I'm not saying the O2 and Evap suggestions are not very common, but without a code and a diagnostic flow tree- your wasting your breath. At least down here, almost any auto parts store has the ability to pull the code for free- thats all you need for now and get back to us.

And yes Scott, after X-amount of drive cycles without repetition - it will clear the code.

Andy

 

[moparbarn]

BINGO!!! get us a code. even though the cel is off, there's still a code in the ecu's history. the parts house's scanner may only read current/light on codes. even though they may not see a code, DO NOT let them clear or 'reset' the ecu. they may want to do it to return the ecu to factory settings (which it will), that will erase the code retained in history.

 

[Rick Sowell]

Ford Senior Master Tech, get me a code and I probably can help you out. It's what I do daily. Rick