my check engine light came on so i took it in to have it looked at . it was the air mass sensor, so i had it replaced and the light reset. it came back on and i had it reset again. today i noticed that it came back on but went off on its own. i thought it was strange so i pulled over and shut the engine. when i turned the key to check the dash lights, the CEL didnt light up. i banged the side of the cluster and it came on. i banged it again and it went off. now its on again, and i can turn it on and off by banging the instrument cluster. why would this happen. a loose wire?? how can i fix this.??

 

it has nothing to do with the loose wire.

it's just a banging coincidence. the instrument cluster cannot behave differently by shock. it is a very compact electronic component.

 

could it be the bulb then?? i can pretty much do it at will now. i hit it, it turns on. hit again, it shuts off. and when its off, it doesnt even light up when the key is turned to the first position on the ignition.

 

But, the instrument cluster has to plug into something. Apparently there's a loose connection. Can it be chip creep, like the old computer daughter boards were cursed with?

I think the CEL is on and the banging turns it off instead of the other way around. If there a fault code then you know the light is trying to stay on when you bang it and turn it off. This would still hold true if the bulb were just loose.

 

i took the car in today and there was a code. it was P0410. something about a sec. air injection??? or thats what i think it said. my mechanic told me it could be a pulse valve?? or that air got into the fuel system. like when u dont turn the car off at the gas station. but i always shut the carn first, so what could it be. the "pulse valve"?? thing was pulsing, so i assume its ok. any ideas??

 

1st, did u ever fix the light? Sounds like the mass airflow sensor was never at fault, did the mech show u the code for the MAF or just change the part? It could have been the P0410 msg from the beginning.
Regarding the P0410 msg, my 99c280 (90k miles) has had it for about 6mos but it is not repaired yet. At 1st it occured occasionally and now it is up to every 2 days. The 'pulse' valve that u speak of could be the 'purge' valve that i replaced with no help. u can have my old one if u want to try it . It is an elex operated pneumatic valve in the eng compt just behind the drivers headlight. The MB mechs claim that the msg is a clogged head and that both heads need to be removed and soaked clean for $2100! i think that the egr valve or tube is clogged and will let u know when i clean it. See previous threads for egr mtc. good luck!

 

mixture too rich or too lean.

the secondary airpump not working sometimes.

open the cover on control unit box on the front left engine compartment. you will see a relay, black color. pull it out and check if the terminal is loose or the relay is faulty... replace it.

 

yes the sir mass was changed. this CEL came on after. the mech did show me both codes. the light situation is the same. still comes and goes when i have the ignition in #1. but no longer turns on while running. i dont think its the purge valve. i can feel it pulsing.(but thanks for the offer) i hope its not the head! let me know how ur car turns out.

 

thanks sleepwalker. i'll try that!. its pouring right now so i'll do it tomorrow. i'll let u know soon. thanks again