: Dtc 420 & 1189



Cadillacboy
12-29-06, 09:11 AM
I have been having those following codes in my car DTC 420 and DTC 1189. A few days ago , those throwed by PCM then cleared them all . Today those same codes are back again and I just cleared the codes again . So , should I worry or shouldn't ?
Car seems pretty nice and with no visible symptoms such as backfire,missfire,dropping MPG ,hesitation.

FrankT
12-29-06, 09:57 AM
I have been having those following codes in my car DTC 420 and DTC 1189. A few days ago , those throwed by PCM then cleared them all . Today those same codes are back again and I just cleared the codes again . So , should I worry or shouldn't ?
Car seems pretty nice and with no visible symptoms such as backfire,missfire,dropping MPG ,hesitation.

P1189=The PCM detects that the oil pressure switch signal circuit is high.
Possible causes, the oil pressure switch is disconnected or a bad switch.

P0420 = The catalytic converter efficiency is too low.
Most likely a degraded catalytic converter.

Frank

caddyman2005
12-29-06, 10:37 AM
for the code 420 the converter is covered for 8 years and 80000 miles by cadillac.

FrankT
12-29-06, 10:45 AM
for the code 420 the converter is covered for 8 years and 80000 miles by cadillac.

Good Point :thumbsup:

Cadillacboy
12-29-06, 10:48 AM
Thanks guys ,for the oil pressure switch can I check it myself or have it checked by dealer ?
BTW car has 55K miles on it

aplusdj1
12-29-06, 11:28 AM
I get these same two codes on my 2002 Seville STS> I also have a new Cat and still get this code.

FrankT
12-29-06, 12:33 PM
I get these same two codes on my 2002 Seville STS> I also have a new Cat and still get this code.

Is it a factory Cat? How old is the cat? A brand new cat can set this code P0420 due to mat burn off, (Green Cat). Clear the code and see it returns.

An engine misfire can kill a good cat in a very short time. Also using fuel with high sulfur content will degrade the cat and set this code. You can try another brand of fuel, clear the code and drive it on the highway to clear any contamination.

P1189 is a circuit code, it should have nothing to do with P0420 which is a catalyst performance code.

Do you have less than 80K miles? If so take to the dealer the cat is still under warranty.

dp102288
12-29-06, 08:48 PM
:yeah: about the warranty. I missed the 80K mile cutoff in our 2000 Seville by 600 miles and the dealer wouldn't fix it. I had the P0420 code too. Never fixed it before getting rid of it.

Cadillacboy
03-24-07, 10:53 AM
I checked the codes again this time DTC 420 was gone but DTC 442 replaced it .
DTC 1189 was on again and cleared them all

jadcock
03-30-07, 09:29 AM
I also have the P1189 on mine. A search here uncovered someone who had it and found a loose connection at the oil pressure switch. That's something I'll check this weekend.

http://www.cadillacforums.com/forums/cadillac-deville-1985-2005-including-1985/91806-pcm-p1189.html?highlight=P1189

http://www.cadillacforums.com/forums/northstar-performance-technical-discussion/43485-code-p1189.html?highlight=P1189