Check engine light turns on then off after restart.

[disavowed10]

Weirdest thing.I have a '91 Civic and i drive for about 10 min. and the Check engine light comes on. So I turn off the car and try to read the code and it's gone! I restart the car and it's gone too. So another 10 min go by and same thing. I dont even wait a min to turn the car back on and it keeps doing it.I'm having issues with passing SMOG. I just cleaned out the EGR and I'm thinking MAP sensor now. Someone mentioned Catalytic Converter. But there is just no way to know! grrrrWhat would cause something to fail after warming up and then restarting after a cool down/restart?

 

[disavowed10]

bumpp

 

[TurboMirage]

need the code yo.

 

[CAFROG]

Based on the EGR cleaned and the code being intermittent, its possible the problem may not be related to the smog situation. Or.....maybe it is? Like the O2 sensor is going bad? Catalytic converter can definitely be a smog issue. Take it off and look inside it. Look for any light coming out of the other end. It may be clogged. In my opinion, there are only fifteen ways to deal with this lol. Here are a few I could think of:

1) I don't think the ECU stores a code so you would need to check the code on the ECU when the light on the dash comes on. My friend told me long ago that the OBD0 has lights on the ECU to read the code.

2) Wait until this becomes a constant issue and check the code.

3) Chase your electrical and look for some bad wire(s) or bust out the multimeter and go to town.

4) Throw some cash/parts at it until it stops. But new O2 sensor and new quality cat are popular parts that are bought to get a car smogged.

 

[luky1380]

obd1 do store the codes but obd0 i dont think so, but i may be wrong
when the CEL comes on get to your ECM(dont turn the engine off) there should be LED light somewhere on it and it should flush when CEL is on(long flushes are tenth and short flushes are ones) so read code and go from there

 

[disavowed10]

So is it possible to read the code while the car is on?Would the paper clip technique work?Lastly is that the idle is pretty rough and shakey. I have a feeling that this could somehow be related to either the SMOG or the Check Engine Light..... Would a MAP sensor cause this? I dont think a 02 Sensor would or a catalytic converter??What do you guys think??thanks!

 

[CAFROG]

Its all too much to ponder without a code off the ECU.....just do that and go from there.

 

[luky1380]

jumping 2pin connector with paper clip will work on OBD1 which is 92-95 years models(unless im wrong please correct me) and your car 91 and its OBD0 so you just have to count flushes of LED light on ECM