Check Engine light

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Oct 12, 2004 | 02:42 PM

eltako

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Check Engine light

Hey everyone,

My check engine light has been coming on in my 94 100cs 2.8 when the car is idling at a stop light for more than a 30 seconds or so. I can drive an hour and it won't come on, but the second it starts idling for a while, it flips on.

I just followed the instructions in the FAQ to get the MIL code, it's 02341, Oxygen Sensor Control

Alldata tells me to try these things:
Auxilary fuse 28 faulty -it's not
Fuel tank empty -it's not
Fuel system pressure to low or too high -how can I tell?
malfunction of spark plugs, connectors, or wires -I replaced all six plugs with bosch platinum +4 and it still does it. The wires and connectors look good
air leak in maf sensor -how can i tell?
leak in exhaust system before twc -it doesn't sound like it has an exhaust leak
oxygen sensor faulty -how can i tell?
evap canistor purge valve sticks -how can i tell?

I appreciate the help, guys!

-Ben

Oct 12, 2004 | 02:55 PM

eltako

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update

Hey,

Sorry, it's code 2331, not 2341.

I noticed there's a small air leak on one of the rubber vacuum lines on the right side of the engine. It's still getting vacuum cuz it I unhook it, the engine dies.

Could this be releted?

Oct 12, 2004 | 07:42 PM

4Driver4

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Yep.

You have a vacuume leak somewhere.

Oct 12, 2004 | 07:50 PM

snowman '92 100

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10$ says your o2 sensors are old. However, the airleak is definitely related, and likely the cause.

Oct 12, 2004 | 09:23 PM

eltako

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update #2

I replaced the leaking vacuum hose, and although the annoying whistling sound it was making went away, it seems to idle a little smoother, the check engine light is still on.

Is there any way to tell how old the O2 sensors are and which of the two need replacing? Need any special tools or anything? Who sells the cheapest ones? Anything else to check

Thanks!

Oct 13, 2004 | 03:29 AM

4Driver4

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If the light is just on at idle, I think you still have a leak somewhere.

Oct 13, 2004 | 04:47 PM

eltako

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What's a good way to find leaks?

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Oct 14, 2004 | 12:04 AM

snowman '92 100

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You should be able to tell if you have a leak on these cars by its idle...

if it jumps around a little and you can feel it vibrate enough to make you think you're in a race car, than you still have a leak. Otherwise, my bet is on old o2 sensors. There isn't really a way to test them to see if they're still good. A major tune up involves changing these. Replace them in pairs. For OEM ones, expect between $130-160 each, need two. For Bosche universals, expect $35-45 each, need two. The universals must be spliced in, preferably soldered conneciton.

If you can afford it, just replace them unless you KNOW they're brand new. These guys are major contributors to gas mileage.