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01 Catera getting P0300 code

14K views 58 replies 9 participants last post by  retho78 
#1 ·
Hi,

My in-laws car had a P0300 code come up (random misfire detected). Where do I start? Could it be the plugs, coil pack or oil leak going into the plugs?


Thanks.
 
#28 ·
okay, thanks. The codes are P0300, P0161 and P0160. I search online and several folks had this same problem and ended up changing the ECM too. I think I can get an exchange on the coil since it was replaced last month and still under warranty.

Previously for the O2 we were only getting P0160 now getting the P0161.

Hope the ECM has not gone bad.
 
#31 ·
how hard is it to change the coil yourself.

and whats more important, pre cat o2 sensors or post cat o2 sensors and will pre cat o2 sensors work as post as well ? can't seem to find post cat o2 sensors for 1998 catera, only pre cat.
would 1999 catera post cat o2 sensors work?
 
#33 ·
ok so using nethic's VIN I pulled up the O2 sensors.

pre-cat aka upstream sensors
#90540984
$243.40 - list price each
$152.13 - forum price each

post-cat aka downstream sensors
#90540985
$232.90 - list price each
$145.56 - forum price each

I have one of each in stock that can be sold at even cheaper prices.
PM me if you are interested (I will need your VIN just to double check and make sure).
 
#36 ·
Just a quick update, I replaced the O2 sensor (bank 2 sensor 2), ignition coil and plugs on the passenger side yesterday. It ran smooth and then the check engine light came on today and it's running rough. I scanned the codes and it's showing random misfire, cylinder 2 and 6 and also showing bank 1 sensor 2 bad. It's very strange after replacing one side coil, plugs and sensor then other side craps out :bonkers:

I feel like the ECM is gone bad causing all this problems. Anyways, I'm going to disconnect the battery tonight and hook it back up tomorrow and see how it does, hopefully resets the system and runs fine.



Thanks.
 
#38 ·
Yeah...I think it's the ECM. I'll check tomorrow and let you know. If there a way to flash/reset the ECM and see if i'll work? If in case the ECM is bad and needs to be replaced what's the best way to go, get a used one and program it to the car or go with a brand new one?


Also, Rippy - any idea how much a valve cover cost on 1998 Catera? Please let me know....thanks
 
#44 ·
The CEL came on today and it didn't show any misfire codes but changed the plugs on the driver's side. The codes were for the O2 sensors bank 1 sensor 2 and also showing bank 2 sensor 2 (I just replaced this sensor earlier this week). My feeling it's the ECM and feel a little roughness on idle.


Thanks.

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For the ECM, what numbers do we have to match to find a replacement? I see so many numbers on the label plus the part #90566574.
 
#45 ·
k your ECM is #9196386
I think that the price I PMd you earlier this week was wrong

the current list price for that ECM is $1,600 (!!!)

I could sell it for $960.18 (but I realize that is still a pretty outrageous sum)

that number or the original number (9117544) are the only two that will work if you're going to try a used ECM
it appears that your ECM is specific to 1998 so you will have to find one from another 1998 Catera

...

sorry for the bad news
 
#46 ·
The ECM I may need replacement is for the 2001 Catera. My 98 Catera is fine only have valve cover leaks.

So the price you pm'd might be right for 2001, not sure just let me know.

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Also, let me know the ECM part number for the 2001 Catera....thanks.
 
#48 ·
No, the VIN # I send was for the 98 (for the valve covers).

I do not have the VIN # for the 2001 at the moment, since it's my in-laws car. I can probably get it by tomorrow but just let me know how much a ECM cost, just an approximate figure is fine.


Thanks.
 
#51 ·
the fuse block cover has a legend that says what's what
owners manuals often also have the same legend (in case the fuse block cover gets lost i guess)

'99-'01 do show that they're the same
as for programming, whoever is doing the work will best be able to answer those related questions

the part number you mention (90566574) does not register as a good part number for me
if you're getting that part number off of the module that would make sense but not really help much
often the part number on the module does not match the parts catalog service part number(s)

you could use it to match other '99-'01 ecms ... but i think they're all the same unless you've got an export engine/vehicle

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and again, with a VIN we can take some of this guesswork out
 
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