Nasty Check engine light went on... solid yellow... code PO300

Whiteheron

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Mazda Protege 4 door sedan
I have a Mazda 2002 Protege Sedan. Last week it had the engine light go on suddenly on the freeway after a sudden loss of power. As you might imagine, I, a woman lacking in automotive smarts, was rather paniced.

I went to the nearest trusted station I could find and they found that some mechanic at a gas station had left my oil cap off...
He found the oil cap at the bottom of the engine compartment, retrieved it and put it back on but did not reset anything. The oil levels were good and the oil quality looked good. (As I had an oil change last month, that was to be expected.)

I turned off the car and when I turned it back on later, I was happy to find that, for awhile, the car was fine, no scary engine light was to be seen. But the light came on solid midway to work the next day when I suddenly had to slow down on the freeway and again there was a little stutter or feeling of drag or loss of power.

It continues to feel good to drive most of the time although there is some minor shaking in the engine but this is rather difficult to distinguish from the bad suspension that I cannot presently afford to fix.

I took it to pep boys today as that was the only place I could find to do a free diagnostic and to turn off that scary yellow light.

I was told the car had two problems... one being the PO300 random multi cylinder misfires and the other being the P0117 Coolant Temperature CKT Low input (I will deal with this in another post.)

When the mechanic popped open the hood, there was a lovely coat of oil on the distributer box... and there was indeed the sound of a intermittant misfires (a few only showing up in idle at the shop but the mechanic said that otherwise it sounded pretty smooth at the higher speeds)

The mechanic was quick to say that he thought it was either or both of these problems... the wires need to be cleaned or one or more spark plugs need to be changed. I am hoping for the cheapest problem possible.

I am wondering what you think and what you would do if you were me, a single woman, uneducated about cars who wants to avoid being shark bait to a dishonest mechanic and who cannot afford to fix anything for at least two more months.

Do you have any suggestions, fix ideas with cost estimates, etc?
 
multi misfire isn't the plugs. it's the coil packs. they're coil on plug, no distributor.

replace the coil packs, check in the spark plug holes to verify that no oil got down there. spray the engine w/ a power washer, be sure not to get water in any sensor/connectors that you can.

good luck!

and fyi, having a solid check engine light isn't horrible.. the one that's bad is the FLASHING yellow!
 
My pocouch to the suggestion of replacement of coil packs...

Sounds like a repair too expensive for me to contemplate.... replacing coil packs...
not going to happen... priced them and it is over $100 no can do.
I can just imagine what the mechanics in my area will charge me....
Wouldn't a simple cleaning of the wires do?
I am praying for cheap and easy fixes... not expensive and difficult ones.
Thanks for the FYI...
Can the repair wait until the 12 of never safely?
 
you can do the coil packs yourself also. the ONLY tool that's needed is a 10mm socket and ratchet. and some elbow grease to pull them out.. you might post a WTB for the coilpacks. see if anyone has them here, lightly used.

you can TRY to clean the wires, but random missfires are generally caused by the coilpacks. or maybe a bad batch of gas?
 
hey i had this problem the other day. advanced auto parts said it was a random misfire too. my car was fine at start up but when driving at constant speed, it would stutter at times.. kinda like the RPM fluctuating. The guy recommended to change either the coils or spark plugs, but he said I should try the spark plugs first since it's cheaper. I changed the spark plugs, which was a PITA. you gotta take off the intercooler to access the plugs. I changed them and after a few hours, the light went off and no stuttering. it didn't come back on.. *knock on wood*
 
you gotta take off the intercooler to access the plugs. I changed them and after a few hours, the light went off and no stuttering. it didn't come back on.. *knock on wood*

Before I saw that you had a 3 I was about to say wtf, for the protege it's much easier.
 
I would like to thank all of you for your help...

I though was extremely lucky as I would not have been able to remove the coils as I know nothing about cars other than driving them and pumping my own gas...

It seems that what was causing my random misfires was bad gas...

I must say that I was surprised by this... I had heard tell of bad gas but did not until now know how bad, bad gas could be.

The car shook, lost power, and almost died several times on the freeway... Now, though, with different gas, it is still a little slower than I would like but it is moving along well and wonder of wonders, no check engine light.

I must admit to being a little embarrassed saying that my car had bad gas... one friend suggested that I perhaps should have used pepto on it... grins.

Now, I would tell people to drive awhile, get gas from a good place and see what happens before racing to change coils, etc. It is certainly a lot cheaper even if it does cause a lot of fear until the bad gas gets out of the system.
 
I would like to thank all of you for your help...

I though was extremely lucky as I would not have been able to remove the coils as I know nothing about cars other than driving them and pumping my own gas...

It seems that what was causing my random misfires was bad gas...

I must say that I was surprised by this... I had heard tell of bad gas but did not until now know how bad, bad gas could be.

The car shook, lost power, and almost died several times on the freeway... Now, though, with different gas, it is still a little slower than I would like but it is moving along well and wonder of wonders, no check engine light.

I must admit to being a little embarrassed saying that my car had bad gas... one friend suggested that I perhaps should have used pepto on it... grins.

Now, I would tell people to drive awhile, get gas from a good place and see what happens before racing to change coils, etc. It is certainly a lot cheaper even if it does cause a lot of fear until the bad gas gets out of the system.
Why should be embarrassed? It's not like you were going to test the gas while you were at the gas station to figure out whether it is good or not... ;)
 

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