check engine light Options

[6strngs]

so, the check engine light on my car lit up. The car still ran fine and everything, I stopped and restarted a couple times today with no problems with anything, everything seemed normal. I think I know what caused it. about a week or two ago, I decided to unplug the hose connecting the EGR to it's source of vacuum. I read about it on mr2oc.com in one of the threads about NA 5sfe power. anyway, after driving around like that for a while, I decided that there was no noticable difference and it just made a wierd sound before 3-4K rpms and might've also been giving me a slightly high idle. so I decided to plug it back in today. but after I did, I noticed that after a while that the yellow light that had lit up on my dash wasn't the fuel light like I thought, but the check engine light. I wanted to get a paper clip and see if I could get a code for it, but I was with my girlfriend today, so I was... occupied. So I was gonna check it right after I got home from dropping her off, but the light went off on my way home. so, the question is, could it have been from reconnecting the EGR? and why would it throw the light to reconnect it? if anything, wouldn't it have thrown the light by disconnecting it?

[Bitter]

the code should still be stored and is likely related to the EGR.

[6strngs]

well, I just disregarded it because it went away. but it came back again today, so I went out and checked it. code 71, which is for the EGR. so I went out, and checked all the hoses and everything, it should be fine! I might try to disconnect the battery to reset the computer to see if that's all it needs. if not, then I have no idea! all I did was unplug the EGR for a while, then I plugged it back in exactly where it came out of...

[Gary]

Try to reset the ECU ans see if the code still show up.
You don't need to disconnect the battery to reset the ECU.
Just remove the EFI fuse (15A blade fuse in the main fuse box) for 10-15 seconds and put it back.
Disconnecting the battery will make you lose clock and radio setting.

And if you want to disable code 71 permanently, just short the pins on the EGR temp sensor.

This post has been edited by Gary: Jan 26, 2007 - 10:33 AM

[bufferdan]

I got a code 71 a couple weeks back and it went away...the the other day it came back on and stayed. Today as i was driving into work the car started running like crap and had no power. Guess im gonna have to clean my egr

[celicaboston1983]

any updates on this my engine light has been on for 2 yrs now for the egr and i tried 3 different egr and it still on. need to get my inspection sticker the place that i usually go stop taking bribes

[alltracman78]

What year is your Celica?
What is the actual code?

[6strngs]

mine is a 94 GT. I pulled the EGR off last night and it was filthy! like the hole that leads to the intake manifold was so clogged that almost no air could get through. so I spent a while cleaning it up. threw it back on, and while I was driving today the check engine light came back on.

it's a code 71. and after searching, it seems that I'm not the only person this is happened to, and in all the threads I saw, nobody actually found a resolution. but, I read somewhere that you can add a resistor somewhere to make the ECU think that the EGR is fine. anybody know how to do that because I need to get a smog soon.

This post has been edited by 6strngs: Feb 15, 2007 - 1:56 AM

[laff09]

What is an EGR? and its function? just curious, thanks

[6strngs]

What is an EGR? and its function? just curious, thanks

satnds for exhaust gas recirculator or something like that. basically it takes carbon dioxide from your exhaust gas and puts it back into your intake manifold. it's to reduce the emissions.

[alltracman78]

yep

Exhaust Gas Recirculation [valve].
It recirculates exhaust gas to your intake man. Which is then sucked into your cylinders. Exhaust gas in your combustion chamber = less combustion = cooler combustion temps.

Cooler temps mean less NOx is formed. NOx is oxides of Nitrogen for those of you that remember chemistry.
Smog/acid rain.

It's only open while you are at part throttle. Never during WOT or idle. Unless something is wrong. A stuck open EGR valve can cause a rough idle, or even make the engine die.

6strngs-You don't need a resistor IIRC. You just need to jump the connector for your EGR temp sensor.
Your problem might be caused by clogged passages in the head/intake man/EGR tube [below the EGR valve], and not the actual EGR valve itself.

[56willysnut]

The ECU will record the code after the 2nd drive cycle showing the fault. Clean your EGR tube, I suspect the EGR sensor is not feeding the ECU with the proper voltage due to a clogged tube or port thru the head. You can however BS the system by installing a 4.7K ohm resistor(bought a radio shack and stuck it in the wiring connector) in place of the EGR sensor, this feeds the ECU the proper voltage it needs and it will not show the fault code. When the engine idles rough the EGR valve is stuck open causing fuel/air mixture problems.

P/N for the resistor if needed is 271-1124 Pkg of 5, $.99 Bend wires of resistor to match width of connector and insert wire into car side of wiring harness for sensor.

This post has been edited by 56willysnut: Feb 16, 2007 - 8:15 AM

[6strngs]

yep

Exhaust Gas Recirculation [valve].
It recirculates exhaust gas to your intake man. Which is then sucked into your cylinders. Exhaust gas in your combustion chamber = less combustion = cooler combustion temps.

Cooler temps mean less NOx is formed. NOx is oxides of Nitrogen for those of you that remember chemistry.
Smog/acid rain.

It's only open while you are at part throttle. Never during WOT or idle. Unless something is wrong. A stuck open EGR valve can cause a rough idle, or even make the engine die.

6strngs-You don't need a resistor IIRC. You just need to jump the connector for your EGR temp sensor.
Your problem might be caused by clogged passages in the head/intake man/EGR tube [below the EGR valve], and not the actual EGR valve itself.

I did clean the tube that came from the bottom of the valve. I also cleaned the inlet where it connects to the throttle body. and I cleaned the filter for the vacuum valve thingy (the valve that sits next to the EGR valve on the intake manifold) I also cleaned off the tip of the sensor because it was crusted over with grime...

[56willysnut]

You may need to clean the lower end port also, runs from the exhaust side of the engine internally to the intake side of the head, remove tube and blow some high pessure shop air into port see if that clears it out.

[alltracman78]

Yep.

The problem is, if ANY of the system is clogged, it can stop flow.
Or your sensor itself could be bad......

[laff09]

Thanks for the information 6strngs and alltracman78, i appreciate when people take time out to explain stuff in such thorough detail.