Check Engine light Flashes ..Loses power
 

2001 Protege...Check engine light flashes and loses power. Engine misses until the car is restarted . Scan indicates codes P0300.."random misfire detected"...also code P0421..."Bank#1 warm-up cat...efficiency below limit." This code unlikely to be connected to problem? The car has been checked by a mechanic and unable to induce the problem....Plugs were changed. Problem still exists. Anyone experience a similar problem?

Could be a bad coil or coils as for the bank one ,check the O 2 sensors , they could be related ,if you are getting a miss fore then you are dumping raw fuel into teh exhaust systen fouling the sensors and possible plugging the cat

CEL flashing and power loss
 

The problem reared its ugly head again today. It seems to always happen about the same length of driving time and when coming to a stop(at a light etc.). I headed for the shop for a scan while the car was running roughly...5 mins. away....and by the time I arrived the car was idling smoothly and light was still flashing. The scan showed same 2 codes ...unable to get scan while running roughly. I am gambling on the coil packs with the mechanics agreement and have the coils and wires ordered. Should know by Fri. if the problem disappears.

Just had the same thing, not flashing but steady on, happened a few times, same code. Replaced the coils on my P5
'03, its been perfect. Check NapaOnline for replacements if your in the US. Unfortunately NapaOnline only deals in the US so I was out of the luck but the coils were $26 US each, where NapaCanada I had to pay $77/each.

Good to hear, Shasta. Thanks for the info...77 also....

I hope that works for you. Oh just a note. On my application I had to swap the original spark plug ends (they just pop off with a spring) the new Napas were a bit too short so make sure they check that, or you do, very easy to swap. Alot cheaper than the $429 bill Mazda wanted and the best part, its the exact same manufacturer and part # to the factory units.

Didn't we figure out (was that on toprotege.com?) that the part number you got wasn't the one napa recommends for the Protege?

But yeah just look and be sure they're the same length.

through my knowledge... flashing engine light usually indicates a bad cat, check the o2 sensors, is its all good.... you might have to get a new cat...

A general, consistent loss of power would indicate a bad cat to me. He got the code read (first post) and it's a misfire code.

That being said, driving a car with a constant misfire WILL destroy your cat, which could produce the second code, which could in fact mean exactly what it says --that your pre-cat (the one under the hood, not the one under the car) needs to be replaced, but as black pointed out, might just be a bad sensor. I know that a Protege will drive just fine (i.e. still getting 35mpg highway) with the second oxygen sensor totally unplugged. It does trigger a CEL of course, but I think it is a different code than P0421.

But seriously, you had a mechanic look at it, you told them the loss of power and misfiring bit, they saw those pretty obvious error codes and said they didn't know what the problem was?

Order of attack:
- replace plugs (8USD)
- replace coils (~55USD, ~154CAD)
- disconnect second oxygen sensor
- replace second oxygen sensor
- inspect cat (how? never had to do this before.. I guess if the internal matter of the cat is all melted you'll know something is wrong)
- replace cat --someone here who has replace it with a header might be willing to sell you theirs, but it's pretty heavy if I recall correctly so shipping would cost you a lot. Depending on the laws of your province (or country) you may still be under warranty for all emissions-related equipment. I think here it's 7 years and some very high mileage number (or unlimited, depends on the state).

There was no other option from Napa in Canada, you had found that number on the US site but no picture so I'm not sure if its the longer one or for the 2.0L at all. Until someone buys the other part # you found will we know for sure if indeed it will work completely.

People have bought that part number.. it's the only one they say works for the Protege5 on their site as well --at least on their U.S. site?

Misfire and cat. alarms
 

The new coils and wires were installed today and so far with about 40 kms. of driving , everything is cool ....no alarms for misfire or cat....I am assuming problem is solved. Thanks to all for your input and suggestions ...and Shasta ...thanks for the tip on Napa coils...swap had to be made ...too short...Cheers....X

Well lets keep our fingers crossed and hope all is well. I had other members point me to the Napa coils as well so if I can do my part to save someone money and get their ride rolling again, that makes me happy.

The check engine light has reappeared , steady. There has been no misfire and I assume that it is for cat. low efficiency. I have not scanned it for a code..The car is running smoothly, however there may have been some damage done to o2 sensors or catalyst.

^^^ Ah shit....I feel bad, hope I didn't steer you wrong. Too bad you were not closer, I had just bought a scan tool. I think kansei mentioned the cat.