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P1189


Mary

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Wow, I've spent the last half hour trying to figure out how to ask a question on here! My car is missing terribly and the code p1189 came up with the service engine light blinking and then solid on. What do I need to do and how important is this? Will it cost me a fortune to fix? Please notify me as the site won't let me turn on the notify switch. My email is maryladwig@rocketmail.com. Any help would really be appreciated!

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P1189 is a engine oil pressure switch open.  That means the engine can't tell if the low oil pressure sensor is working or not.  Please check the engine oil level manually before operating the car. 

Are you getting any other codes? A misfire should register DTCs.

Quote

DTC P1189 Engine Oil Pressure (EOP) Switch Circuit  

The low oil pressure sensor is normally closed. When oil pressure increases above 1 to 4.5 psi the switch contacts open. The powertrain control module (PCM) supplies 12 volts to the oil pressure input circuit. With low oil pressure the 12 volts is pulled low to ground. This diagnostic tests for an open condition of the oil pressure switch circuit. If the engine has been off long enough for engine temperature to drop by 10°C (50°F), then a shorted, low oil pressure, condition of the circuit should be observed prior to engine running. If the engine has not been cranked and oil pressure has been detected DTC P1189 will set.

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Bruce

2023 Cadillac CT4-V Blackwing

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Bruce, I did check the oil and I was down 2 quarts. I added it but it didn't fix the problem. I also have a code U1255. Thank you for answering so quickly. I read what the code means, but I don't really understand. I just really am wondering if this is serious and expensive to fix. This car is killing me! I love it but I don't have a mechanic and I keep getting ripped off.

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Hi, :welcomesmiley:

If the oil level is correct I would suspect the oil pressure switch is defective. 

What is puzzling is the engine miss and no corresponding DTC's. Please recheck all DTC's and post here. After you do the check, disconnect the battery and touch the cable ends together to reset all the modules. Reconnect the battery and let us know what happens.

THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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The  U1255  is a Class 2 Communication Malfunction (Serial Data Line Malfunction).  The Cadillac uses a common communication bus or interface that each of the different electronic modules communicates across.  One of them is not communicating properly and is 'blocking' the bus with constant signal or noise.   This is often an intermittent code that might tell us more in concert with other codes, but isn't that useful alone.

We are expecting a P300 code or similar for misfire.   If the car was operated at low oil level (you note down 2 quarts) then that could cause catastrophic failure which might give the same symptoms as a misfire.  In that case we would also expect to see a timing related code if the timing chain had broken or the engine was otherwise no longer in good timing.

Can you describe how the symptoms first started? Hopefully others will chime in with other suggestions  @OldCadTech

 

Bruce

2023 Cadillac CT4-V Blackwing

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Oh wow, I do have a 0300 code! I'm sorry, I completely forgot to mention that! Lol, I'm so NOT a mechanic! It's hasn't stalled it anything but I can feel the misfire! I will try disconnecting  the battery thing!

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Yes, disconnect the battery, P0300 is a random misfire. 

THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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If the ses light if flashing its a current misfire that needs to be addressed. You need a good scanner to find out what cylinder is missing or a good mechanic that can diagnosis what cylinder is misfiring 

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Okay, I'm going to run down and check all of the codes. I'm sorry, bare with me please. It's there anything I can break when I touch the cable ends together on the battery?

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What year car is this?

Sounds like a coil pack 2000/01

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Be sure the cables are not connected to the battery and touch the cable ends together for a couple of seconds.

THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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Okay, here are all of the codes. B0300 current, U1255 current, 1348 history and 1341 history. I should mention that the day after the check engine light came on and I found the codes and added the oil my car started running hot. It never overheated I should mention. Anyway, a mechanic found my radiator hose wasn't connected. He fixed that but didn't check the codes for me. So now, the car runs well except the misfiring.

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2 minutes ago, OldCadTech said:

Be sure the cables are not connected to the battery and touch the cable ends together for a couple of seconds.

so to be clear, 

Quote

After you do the check, disconnect the battery and touch the cable ends together to reset all the modules. Reconnect the battery and let us know what happens.

means to disconnect both the positive cable, and the negative cable from the battery.  Then, with NOTHING connected to the battery, touch the positive cable and the negative cable together.  The goal is to ground out the system.  Then reconnect the positive cable to the positive post, the negative cable to the negative post.  Ensure during this operation the battery itself is not connected to anything.

Please don't simply short across the posts of the battery or with the battery connected attempt to connect the cables in any other way.  Be careful around the battery as batteries often vent vapors which are highly flammable.

Bruce

2023 Cadillac CT4-V Blackwing

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1 minute ago, OldCadTech said:

@BodybyFisher I went by the model and year in the OP bio

 

Thanks I dont get that info on the android app.  What year is it?

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Ok I see it, 99, I needed to go into her profile

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Sorry, you're right, it's a 99 DeVille. Okay, so.... That was no easy task for me! I didn't have a wrench so I had to buy one to take the cables off. Then some guy was walking by and decided I was a damsel in distress and INSISTED on helping me. I must've looked really pathetic!  So, he made me wait an hour before he would reconnect the battery. So annoying! Anyway...I drove it around to see if it was fixed but the SES light came on again. I ran the codes and this is what I got. 0300H, 0603H, 1552H, 1255C, 1341H, 1348H, 1558H.

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Is the vehicle displaying P0300 History, P0603 History etc...?

If so the codes should have a letter designation first ie - P, B, U  ....

They go by pretty quick, if you can take a video with your cell it may help so you can play it back.

If you want, YOU can disconnect the battery cables again and touch the cable ends together to reset the modules. Drive it again and see what happens.

THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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Are you using the onboard diagnostics to check codes or a 3rd party code reader?  Usually there is a first letter like P or A to indicate which system the xxxx code belongs to.  H or C would appear to be History or Current, so that helps.

 I am guessing at the letters based on possible values:

P0300 history engine misfire

P0603 history  Control Module Long Term Memory Reset (battery was disconnected) nothing to worry about

B1552 Keep Alive Memory (KAM) Error (battery was disconnected) won't cause misfire

C1255 EBCM Internal Malfunction (ABS/TCS Disabled)  won't cause misfire

ACM B1340 - Air Mix Door #1 Movement Fault (drivers, lower actuator) won't cause misfire

ACM B1341 - Air Mix Door #2 Movement Fault (passenger, upper actuator) won't cause misfire

B1558 BCM EPROM Checksum Error won't cause misfire

Bruce

2023 Cadillac CT4-V Blackwing

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:unsure: I'm not seeing anything that would cause the SES message to illuminate. ABS message maybe but not SES

THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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