1999 Miata - Check Engine - Help

I need a few words of wisdom about my '99. It has 65K miles on it. About
a week ago I did something that I believe was very stupid. I cleaned my
engine by hosing it down. The car ran ok for a little while, but then
stopped. The engine light was on. Yes - you guessed it. Water in the plug
wells. Ugh! I spend the time to remove the water and dry the wires & plug
wells. The car was running fine for another few days afterwards and then
the check engine light returned. The autozone tech told me the trouble
shooting error code is P0420., which is: "Catalyst efficiency low-bank
.. - the oxygen sensors monitor the catalytic converters ability to store
oxygen.
Possible causes a
1. Catalytic converter defective (Failure possibly due to #2, 3, or 4);
2. Engine msfire or running condition;
3. Large vacuum leak;
4. Engine oil leakage into exhaust-value guide seals, piston rings

Any suggestions on approach to uderstanding and fixing the problem?

I've been considering replacing the plugs & wires. Is this the correct
first step?

Thanks,
- Pat

On Thu, 14 Feb 2008 01:38:58 GMT, "Pat Dreiding"
> wrote:

>I need a few words of wisdom about my '99. It has 65K miles on it. About
>a week ago I did something that I believe was very stupid. I cleaned my
>engine by hosing it down. The car ran ok for a little while, but then
>stopped. The engine light was on. Yes - you guessed it. Water in the plug
>wells. Ugh! I spend the time to remove the water and dry the wires & plug
>wells. The car was running fine for another few days afterwards and then
>the check engine light returned. The autozone tech told me the trouble
>shooting error code is P0420., which is: "Catalyst efficiency low-bank
>. - the oxygen sensors monitor the catalytic converters ability to store
>oxygen.
>Possible causes a
>1. Catalytic converter defective (Failure possibly due to #2, 3, or 4);
>2. Engine msfire or running condition;
>3. Large vacuum leak;
>4. Engine oil leakage into exhaust-value guide seals, piston rings
>
>Any suggestions on approach to uderstanding and fixing the problem?
>
>I've been considering replacing the plugs & wires. Is this the correct
>first step?
>
>Thanks,
>- Pat

Hi Pat,
I'd suggest that after a drowning, that the most likely fault is the
misfire (of course).
If it was me, I'd be spending time checking and drying ignition
components yet again before spending cash.
Don't know the '99 model but under the distributor cap in most cars is
a good place to start.




OzOne of the three twins

I welcome you to Crackerbox Palace.

Pat, do this first !!!!!!!!

Check that there is NO water in the O'2 connectors. (blow out with air)

Go back and remove the "ground cable" from the batt. ( I don't know if
your radio needs a code to restart, but find out what it is before you
do this!)
Wait about 5 mins. and put the cable back back on.
Reset all of your radio stations :-) and start your car. " IF " the
code comes back, then go start looking at other items to cure the
problem.

Removing the cable, lets the computers reset themselves and many times
that is all you need to do.

Good luck and I hope this helps.

Bruce Bing '03 LS

Bruce,

Will do as long as you can point me in the right direction. How do I access
the O'2 connectors and recognize them.
It's not in the index of my workshop manual. Could they be called something
else? I didn't find anything in the miata.net garage to help. Are the
connectors hoses or wires. Sorry for all the questions. I don't know where
to look.

Thanks,
- Pat

"BRUCE HASKIN" > wrote in message
...
> Pat, do this first !!!!!!!!
>
> Check that there is NO water in the O'2 connectors. (blow out with air)
>
> Go back and remove the "ground cable" from the batt. ( I don't know if
> your radio needs a code to restart, but find out what it is before you
> do this!)
> Wait about 5 mins. and put the cable back back on.
> Reset all of your radio stations :-) and start your car. " IF " the
> code comes back, then go start looking at other items to cure the
> problem.
>
> Removing the cable, lets the computers reset themselves and many times
> that is all you need to do.
>
> Good luck and I hope this helps.
>
> Bruce Bing '03 LS
>

I don't know how may miles are on your 99.
The 420 code can be caused by misfiring, which can kill the converter if not
corrected .
It also is sometimes caused by a bad O2 sensor (front or rear)
Since the front sensor is more likely to fail than the rear, and if
everything else has failed,
Try replacing the front sensor before you spring for a converter.

"Pat Dreiding" > wrote in message
news:V0Psj.1238$%g.806@trnddc08...
> Bruce,
>
> Will do as long as you can point me in the right direction. How do I
access
> the O'2 connectors and recognize them.
> It's not in the index of my workshop manual. Could they be called
something
> else? I didn't find anything in the miata.net garage to help. Are the
> connectors hoses or wires. Sorry for all the questions. I don't know
where
> to look.
>
> Thanks,
> - Pat
>
> "BRUCE HASKIN" > wrote in message
> ...
> > Pat, do this first !!!!!!!!
> >
> > Check that there is NO water in the O'2 connectors. (blow out with air)
> >
> > Go back and remove the "ground cable" from the batt. ( I don't know if
> > your radio needs a code to restart, but find out what it is before you
> > do this!)
> > Wait about 5 mins. and put the cable back back on.
> > Reset all of your radio stations :-) and start your car. " IF " the
> > code comes back, then go start looking at other items to cure the
> > problem.
> >
> > Removing the cable, lets the computers reset themselves and many times
> > that is all you need to do.
> >
> > Good luck and I hope this helps.
> >
> > Bruce Bing '03 LS
> >
>

In article >,
(BRUCE HASKIN) writes:
> Pat, do this first !!!!!!!!
>
> Check that there is NO water in the O'2 connectors. (blow out with air)
>
> Go back and remove the "ground cable" from the batt. ( I don't know if
> your radio needs a code to restart, but find out what it is before you
> do this!)
> Wait about 5 mins. and put the cable back back on.
> Reset all of your radio stations :-) and start your car. " IF " the
> code comes back, then go start looking at other items to cure the
> problem.
>
> Removing the cable, lets the computers reset themselves and many times
> that is all you need to do.

Or you might try this one.

Now you need to clear your 'Check Engine' light. There are a couple of
ways to do this. The easiest is probably just to pull the BTN1 fuse in
the fusebox located under the hood on the passenger side for about 30
seconds. If you pull it out too short, you won't reset the code. If you
pull it out too long, you'll lose your radio presets.

Until I purchased a code reader of my own I used to havce to do this
regularly and I never lost my radio presets.

To be honest, you can buy a code reader of your own for about what
Mazda will charge to reset the CEL once. Considering that something
as simple as not tightening the gas cap (do you ever have someone
else pump your gas?) can turn it on, it is a good thing to carry
int he glove box of a Miata.

bill

--
Bill Gunshannon | de-moc-ra-cy (di mok' ra see) n. Three wolves
| and a sheep voting on what's for dinner.
University of Scranton |
Scranton, Pennsylvania | #include <std.disclaimer.h>

Thank you all for your advice & wisdom.

I did a two step replacement of the Plugs & Plug Wires. I purchased plugs
and wires from Autozone. The more expensive ones.
The next morning I disconnected the battery and replaced the plugs.
Couldn't replace the wires because the #1 & #2 replacement wires were too
short! I reinstalled the old wires, reconnected the battery, returned the
autozone wires and drove to NAPA.
The check engine light stayed off! Problem fixed. At NAPA, I asked for
their set of wires and found them to be too long!

Later that day I purchased wires from Mazda. They too were a little longer
than the originals.
These are working fine, the check engine is off. Not sure the wires really
needed replacing, but @ 65K it's the safe thing to do.

It gives a great comfort that this news group is here!
Again, Thank you all.

- Pat

P.S. Next "Service" I have to concern myself with is the Timing Belt.
I'll let Mazda do it unless someone has a recommendation in the Plano, Tx
area.


"Pat Dreiding" > wrote in message
news:SYMsj.343$Cs.318@trnddc04...
>I need a few words of wisdom about my '99. It has 65K miles on it. About
>a week ago I did something that I believe was very stupid. I cleaned my
>engine by hosing it down. The car ran ok for a little while, but then
>stopped. The engine light was on. Yes - you guessed it. Water in the plug
>wells. Ugh! I spend the time to remove the water and dry the wires & plug
>wells. The car was running fine for another few days afterwards and then
>the check engine light returned. The autozone tech told me the trouble
>shooting error code is P0420., which is: "Catalyst efficiency low-bank
> - the oxygen sensors monitor the catalytic converters ability to store
>oxygen.
> Possible causes a
> 1. Catalytic converter defective (Failure possibly due to #2, 3, or 4);
> 2. Engine msfire or running condition;
> 3. Large vacuum leak;
> 4. Engine oil leakage into exhaust-value guide seals, piston rings
>
> Any suggestions on approach to uderstanding and fixing the problem?
>
> I've been considering replacing the plugs & wires. Is this the correct
> first step?
>
> Thanks,
> - Pat

On Feb 15, 2:56 pm, "Pat Dreiding" > wrote:
> Thank you all for your advice & wisdom.
>
> I did a two step replacement of the Plugs & Plug Wires. I purchased plugs
> and wires from Autozone. The more expensive ones.
> The next morning I disconnected the battery and replaced the plugs.
> Couldn't replace the wires because the #1 & #2 replacement wires were too
> short! I reinstalled the old wires, reconnected the battery, returned the
> autozone wires and drove to NAPA.
> The check engine light stayed off! Problem fixed. At NAPA, I asked for
> their set of wires and found them to be too long!
>
> Later that day I purchased wires from Mazda. They too were a little longer
> than the originals.
> These are working fine, the check engine is off. Not sure the wires really
> needed replacing, but @ 65K it's the safe thing to do.
>
> It gives a great comfort that this news group is here!
> Again, Thank you all.
>
> - Pat
>
> P.S. Next "Service" I have to concern myself with is the Timing Belt.
> I'll let Mazda do it unless someone has a recommendation in the Plano, Tx
> area.
>
> "Pat Dreiding" > wrote in message
>
> news:SYMsj.343$Cs.318@trnddc04...
>
>
>
>
>
> >I need a few words of wisdom about my '99. It has 65K miles on it. About
> >a week ago I did something that I believe was very stupid. I cleaned my
> >engine by hosing it down. The car ran ok for a little while, but then
> >stopped. The engine light was on. Yes - you guessed it. Water in the plug
> >wells. Ugh! I spend the time to remove the water and dry the wires & plug
> >wells. The car was running fine for another few days afterwards and then
> >the check engine light returned. The autozone tech told me the trouble
> >shooting error code is P0420., which is: "Catalyst efficiency low-bank
> > - the oxygen sensors monitor the catalytic converters ability to store
> >oxygen.
> > Possible causes a
> > 1. Catalytic converter defective (Failure possibly due to #2, 3, or 4);
> > 2. Engine msfire or running condition;
> > 3. Large vacuum leak;
> > 4. Engine oil leakage into exhaust-value guide seals, piston rings
>
> > Any suggestions on approach to uderstanding and fixing the problem?
>
> > I've been considering replacing the plugs & wires. Is this the correct
> > first step?
>
> > Thanks,
> > - Pat

Check out cartalk.com. They have a link on their site where you can
find a good shop in your area.

After replacing the plugs & wires the problem went away for about 30 miles.

It's back. What's my next step?
How do I check the O2 sensor?
Do I replace the Catalytic Converter?

Where's the best place to get replacement parts (O2 sensor, Catalytic
Converter)?

Is this something I can easily do myself?

Thanks,
- Pat

"Pat Dreiding" > wrote in message
news:SYMsj.343$Cs.318@trnddc04...
>I need a few words of wisdom about my '99. It has 65K miles on it. About
>a week ago I did something that I believe was very stupid. I cleaned my
>engine by hosing it down. The car ran ok for a little while, but then
>stopped. The engine light was on. Yes - you guessed it. Water in the plug
>wells. Ugh! I spend the time to remove the water and dry the wires & plug
>wells. The car was running fine for another few days afterwards and then
>the check engine light returned. The autozone tech told me the trouble
>shooting error code is P0420., which is: "Catalyst efficiency low-bank
> - the oxygen sensors monitor the catalytic converters ability to store
>oxygen.
> Possible causes a
> 1. Catalytic converter defective (Failure possibly due to #2, 3, or 4);
> 2. Engine msfire or running condition;
> 3. Large vacuum leak;
> 4. Engine oil leakage into exhaust-value guide seals, piston rings
>
> Any suggestions on approach to uderstanding and fixing the problem?
>
> I've been considering replacing the plugs & wires. Is this the correct
> first step?
>
> Thanks,
> - Pat

Glad that I am not a mechanic type. I would have just paid the 200, 300,
or 400, whatever dollars at been done already>LOL.