CarTalk.com Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

2000 mazda miata cel, possible catalytic converter and coil pak trouble

Car recently acted like it was running on two or three cylinders and cel came on and continued to flash. The shop that did the repairs is no longer a Mazda dealer, but has a factoy trained tech. Don’t know the code #, but was told that there was a low voltage code, and a misfire code. The battery was replaced, throttle body cleaned and a new fuel filter installed. The cel came back on about 25 miles later. They rechecked the codes. Said it could be the converter, and cleared the code again. After about 150 miles, the cel came on again but the car ran normal. Talked to the shop again and was told the the converter problem would have to be serviced at a Mazda dealer. The engine did the running on three cylinder thing again. Since then, it seems to run ok but the light is still flashing. If the OEM converters are fragile are there better options for replacement? The car has 30,000 miles. Is this a dealer only fix? Thanks for the help.

See if you can get the actual codes. They will be in the format P#### (like P0123)

Come back and post those codes when you get them.

That CEL (check engine light) is just a kid in class waving her hand trying to get you attention because she has the answer. You need to have the codes read. Some places will read them for FREE. Try Autozone or Advanced Auto Parts. Get the exact code (like P0123) not just their translation into English and post it back here.

Got the codes from the dealer that worked on the car today. P0300,P0420,and P0455. When I drove the car to the shop today, about 2 miles, the light blinked but the car ran normal. When I pulled it up to the tech’s service bay, the light was on but not blinking. He got the codes for me and cleared them out. Pulled the car next door where I am a mechanic at a motorcycle dealership. Went to come home and as soon as I started the car, it again acted like it wasn’t running on all cylinders. Instead of revving it up to try to clean it out, I just let it idle, then tried starting it several more times. Still acted the same. Went inside to get my timing light to see if any particular cylinder wasn’t firing. Just as I was hooking it up, the engine smoothed out and started running normal and no cel ever came on. Hooked the light to each cylinder and all were firing now. It ran normal going home. When starting it back up to put it in the garage, it acted up once more. Didn’t rev it, shut it off and tried it again and it was normal. Still no cel. I have read that when water gets into the plug cavities, they can jump a spark to the head and cause damage to the coil pac. Got water in #4 plug hole a long time ago and had to replace the plugs and wires. Maybe lingering effects and the coil pac may be failing? Again thanks for the help.

I would suspect you cat converter is fine, the code is probably appearing because the engine is misfiring. These cars are know to be rough on plug wires, I would suspect something simple like a bad wire that is causing the intermittent rough running.

P0300 is the main clue.
Check the fuel pressure. If possible leave a gauge on so you can check it when it acts up.
Low voltage? Check out the alternator and belt. Try to measure bat/system voltage when it acts up.
How do the plugs look?
Fix P0300 and P0420 will hopefully go away.
Is there a vacuum diaphragm on the fuel pressure regulator?
Check that it’s not leaking gas into the vacuum line.
Could that cause P0455? I don’t know.