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Wife's 2008 CTS CEL is on - P2601


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CEL is lit on our 2008 CTS AWD DI. Code is P2601 "coolant pump ctrl range/perf"

The aux water pump was bad (seized up, board burnt). I replaced it and confirmed it is working (heard/felt it running after the car was shut off).

Reset the CEL, it stays off for 3 days, comes back on. Found a bulletin that described the issue with a software update:

"
2008 CTS – Check Engine Light, P2601/P2610
Some 2008 CTS and STS models with the 3.6L Direct Injection engine have had the check engine light come on with diagnostic trouble codes p2601 or 2610 stored in the ECM. GM has issued a software upgrade that may eliminate this condition. Your dealer has access to service bulletin #07-06-04-024 which outlines the procedure for upgrading the software in the ECM. In the case of diagnostic trouble code P2601, your dealer should first check the operation of the auxiliary coolant pump, and if no problems are found, the software upgrade can then be implemented."

Had the local dealership run the update/reset the light (out of warranty, but they discounted the labor to about $70).

Three days later the light is back on again.

any advice?

thanks in advance!

Crystal Red Tintcoat Exterior | Shale/Brownstone Interior | 32k

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I would say that it seems that they were unaware of the TSB, but that they were easy on you and you have a good relationship with them. So, why not call the service representative and tell him about the recurring code and the pop-up, and give him the number of the TSB? As a GM dealer, they have to get their TSBs from GM, but with the number it's a simple thing for them to do. If you say "please," they will probably download the TSB and either upgrade it for free or charge you actual time spent by the tech on a clock rather than a flat-rate based fee.

I had a deflection shield come off my car this week. It was damaged from previous wear and tear so I didn't want to re-use it. The estimate gave me a break on the price of the part. They were fresh out but ordered them and had them the next day, and called to tell me and offer to set up an appointment - but I already had an appointment for this morning. When the car was ready, the bill was several dollars under the estimate.

Cadillac dealers really try to keep their customers happy. But, nothing is perfect, unfortunately. Do your part when things don't go perfectly and they will do theirs.

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-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Thanks Jim.

The dealership already installed the updated software as per the TSB at a charge of $70 (originally they said it would be $115). This was after I had already installed the new aux water pump myself.

Wife just called, said the car came up and gave a msg about overheating and went into limp mode. She shut the car off for a few mins. I had her restart the car and it behaved the rest of the way home (the temp needle stayed just below the middle line like it normally does. Doesn't seem that a few mins would be enough to cool it down if it were truly overheating, maybe we have a sensor issues here and a 'reboot' temporally fixed the issue.

Had my wife hook up the code reader when she got home. Still have P2601, but now we have a new code: P1258. Thoughts? This is the first time we've ever had it overheat. Although when I test drove it the other day after replacing the aux water pump I watched the temp guage spike up pretty high for a few mins only to drop back to normal very quickly.

Could something like a coolant temp sensor be the issue here?

Crystal Red Tintcoat Exterior | Shale/Brownstone Interior | 32k

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P1258.... Engine Coolant Over Temperature

Protect Mode Active, Engine running.

The PCM detected an Engine Metal Over-Temperature condition (ECT sensor input more than 268°F)

Thanks, that's what I was finding too....

It's just strange that essentially shutting the car off/back on 'fixed' the issue. No more 'overheating' - no more limp mode.......it couldn't have really overheated & recovered that quickly right?

Crystal Red Tintcoat Exterior | Shale/Brownstone Interior | 32k

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P1258.... Engine Coolant Over Temperature

Protect Mode Active, Engine running.

The PCM detected an Engine Metal Over-Temperature condition (ECT sensor input more than 268°F)

Thanks, that's what I was finding too....

It's just strange that essentially shutting the car off/back on 'fixed' the issue. No more 'overheating' - no more limp mode.......it couldn't have really overheated & recovered that quickly right?

I wouldn't THINK so...

If you think it may be a flaky sensor input... I think I would reboot the entire electrical system.

Remove BOTH battery cables... negative cable FIRST...

Touch both cables together for 5 seconds or so, making sure they have good contact with each other.

This will drain all the capacitors in the system.

Re-attach the battery cables... negative cable LAST...

You will have to do the window EXPRESS UP learn again and you MAY have to do the memory seat settings again.

Sometimes they will forget the seat settings and sometimes they don't.

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I think that sounds like a good place to start. It sticks that it takes three days each time for the CEL to come back on.....so you have to wait a while each time to see if the issue had been resolved. Fun stuff.

At the risk of throwing random parts (and money) at the car, if the reset doesn't fix it I'm leaning towards replacing the coolant temperature sensor....it's an easy and cheap fix.

Crystal Red Tintcoat Exterior | Shale/Brownstone Interior | 32k

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CEL is lit on our 2008 CTS AWD DI. Code is P2601 "coolant pump ctrl range/perf"

The aux water pump was bad (seized up, board burnt). I replaced it and confirmed it is working (heard/felt it running after the car was shut off).

Reset the CEL, it stays off for 3 days, comes back on. Found a bulletin that described the issue with a software update:

"2008 CTS – Check Engine Light, P2601/P2610

Some 2008 CTS and STS models with the 3.6L Direct Injection engine have had the check engine light come on with diagnostic trouble codes p2601 or 2610 stored in the ECM. GM has issued a software upgrade that may eliminate this condition. Your dealer has access to service bulletin #07-06-04-024 which outlines the procedure for upgrading the software in the ECM. In the case of diagnostic trouble code P2601, your dealer should first check the operation of the auxiliary coolant pump, and if no problems are found, the software upgrade can then be implemented."

Had the local dealership run the update/reset the light (out of warranty, but they discounted the labor to about $70).

Three days later the light is back on again.

any advice?

thanks in advance!

Hello davedog,

I apologize that you are experiencing a reoccurring issue with your Check Engine Light on your CTS. Could you private message me your name, contact info, VIN, mileage and dealership you are working with? I would like to speak with them concerning this situation. Thank you very much for your time.

Gregory W.

Cadillac Customer Care

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Gregory: If I can't figure this out and end up doing the dealer route I sure will contact you. I've not had great luck with the local dealership over all, they are nice enough but don't usually get it right on the first try - but so far it's always been warranty stuff so it's no money out of my pocket. So if it has to come out of my pocket I want it right the 1st time.

Now for an update on the issues at hand:

I pulled the battery cables, and touched them together for a few seconds, then just left them unhooked for about an hour while I had dinner. Before I hooked them back up I tested the relay for the Aux Water Pump, seems to be within spec, but I noticed the horn uses the same exact relay so I swapped them in case the relay has an intermittent issue. I guess if the horn starts going crazy....

It always takes exactly 3 days for the CEL to come back on, so I guess I get to wait until Mon night to find out.

Now, as far as the overheating goes...

Took it for a test drive after the battery reset, temps seemed normal, but after that I let it run sitting in the driveway for about 10 mins and it started overheating again...I feel stupid....but it looks like I was low on coolant. I've had the car for 5 years and have never thought to check the coolant level (never had a reason to) combine that with the fact that I did loose some coolant while changing the aux water pump (although I didn't feel like it was all that much)....and i was about a gallon low on coolant! So I bought some of the 50/50 premixed dexcool and topped it off. Wife traveled about 60 miles today, no issues so far.

So while I doubt the low coolant could cause the water pump CEL to come on.....maybe I'll get lucky....

Crystal Red Tintcoat Exterior | Shale/Brownstone Interior | 32k

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Gregory: If I can't figure this out and end up doing the dealer route I sure will contact you. I've not had great luck with the local dealership over all, they are nice enough but don't usually get it right on the first try - but so far it's always been warranty stuff so it's no money out of my pocket. So if it has to come out of my pocket I want it right the 1st time.

Now for an update on the issues at hand:

I pulled the battery cables, and touched them together for a few seconds, then just left them unhooked for about an hour while I had dinner. Before I hooked them back up I tested the relay for the Aux Water Pump, seems to be within spec, but I noticed the horn uses the same exact relay so I swapped them in case the relay has an intermittent issue. I guess if the horn starts going crazy....

It always takes exactly 3 days for the CEL to come back on, so I guess I get to wait until Mon night to find out.

Now, as far as the overheating goes...

Took it for a test drive after the battery reset, temps seemed normal, but after that I let it run sitting in the driveway for about 10 mins and it started overheating again...I feel stupid....but it looks like I was low on coolant. I've had the car for 5 years and have never thought to check the coolant level (never had a reason to) combine that with the fact that I did loose some coolant while changing the aux water pump (although I didn't feel like it was all that much)....and i was about a gallon low on coolant! So I bought some of the 50/50 premixed dexcool and topped it off. Wife traveled about 60 miles today, no issues so far.

So while I doubt the low coolant could cause the water pump CEL to come on.....maybe I'll get lucky....

Hello davedog,

Thank you for replying and I will be looking for your message or update on this thread. I hope you’re your recent work solves your concern! Please continue to keep us updated. Thank you very much for your time.

Gregory W.

Cadillac Customer Care

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Thanks again Gregory.

OK, so the latest:

When I got home from work today I checked the coolant tank in my wife's car again (since she had been driving the car around all day). It was an inch or two below the cold level line, so I'm not sure if air is still working it's way out of the system or what. Still an improvement from yesterday where that tank was bone dry!

Also an improvement; yesterday's test drive resulted in the temp gauge running between 200 and 240 at highway speeds, then nearly overheated while idling in the driveway (260 degrees!). This was before I had discovered the coolant was low. Tonight I took her for another highway test drive, again pushing her pretty hard. This time it never left 200 degrees.....and I let it sit in the driveway for 15-20 mins idling, still never left 200 degrees. So now I'm just waiting for it to cool down so I can check the coolant level again.

I have looked hard and can find no signs of a leak, so again, I'm hoping it was just low from the aux pump change. Also the CEL is still off, but I have to wait until about monday to see if that is really fixed.

Crystal Red Tintcoat Exterior | Shale/Brownstone Interior | 32k

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davedog - go ahead and do as Gregory suggests! You have a guardian angel. These people do *not* make things unpleasant for dealers, and they can open channels for GM help that the particular service people didn't know about or weren't using, and do other good things for you and your dealer.

Oh, by the way, I think you should check the wiring and connector the ECT sensor.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Just to follow up, I think we're good now.

I've checked the coolant for several days now, and it's now holding steady. It is also no longer overheating. Once I realized the coolant was low, between what I added the first time, and what I added after she drove it for a day (and I guess worked the rest of the air out of the system), it was about 1.5 gallons low! Now I don't think I lost that much when I changed the aux water pump, but I may have lost more than I realized, and really don't know how much was in there to begin with - may have already been low. It's not leaking and it's not loosing any.

The CEL light is still OFF! Since the pump seized and even after it was replaced the CEL would always come back on after 3 days. Today is day 4. the only thing is I broke the cardinal rule of troubleshooting and did a few things at once so I'm not sure which one fixed the P2601 "coolant pump ctrl range/perf" CEL:

-Topped off coolant (maybe the cooland being so low, made the pump run more/faster/different and threw the code?)

-Reset the electrical as per Texas Jim's instructions/suggestion (originally did this because we thought there was a coolant sensor issue, but maybe it worked out a glitch in the aux pump monitoring circuit?)

-Swapped the horn relay with the aux water pump relay in an effort to check for an intermittent relay issue (the horn is working fine so it's doubtful that this was what fixed it but who knows)

Even though I'm not exactly sure what fixed the CEL I don't really care. It works!

Crystal Red Tintcoat Exterior | Shale/Brownstone Interior | 32k

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The horn is worked a lot less often than the auxiliary water pump, and this was an intermittent problem so I have my doubts about the relay that you put on the horn. Relays are cheap, and most of them on the car are the same SPST four-prong part. I would just buy a sack of them online to save on the shipping and keep them with the tools, and replace the on you put on the horn. You can give them out as birthday gifts if you don't need them.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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You can give them out as birthday gifts if you don't need them.

Totally blaming this on you if the wife doesn't like her relay this year! :bday:

Crystal Red Tintcoat Exterior | Shale/Brownstone Interior | 32k

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I like giving them out at baby showers. That way my wife says I don't have to go.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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The hard part is pretending that you don't understand the problem.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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  • 4 weeks later...

First post, so if I screw up don't hesitate to tell me. I get the P2601 and check engine light every couple of weeks on my 2008 STS 3.6L DI. The temperature guage never goes above the middle (longest) mark. The coolant level in the plastic overflow tank is always normal. There is no indication of overheating other than maybe the fact that the cooling fan comes on within a minute or three after starting the car. Since I am new to the car (or vice versa), I'm not sure if that is normal or not. I believe I have found the aux pump at the driver side front "corner" of the engine. Is the correct?

My OBD scanner is one of the simple ($65) Innova products which lets me shut off the "Check engine" light, but when I try to erase the P2601 it reads "FAILED) even though the light goes out. I am looking for one of the units that connects to a laptop. (I have an ancient Jeep Wagoneer which a friend and I completely modernized (took it entirely apart and rebuilt the entire car with the newest components available--aluminum heads, hot cam, headers throttle body four barrel EFI etc.) I got very good at tuning the fuel map with a Windows PC.

I noticed one of the previous posts mentioned exact temperatures. Does the CTS guage cluster show temps while the STS doesn't?

Exactly what does disconnecting the battery and touch the cables together do? It is not the first time I have heard of doing this, but I really don't understand what gets reset by doing it. If it includes the seat position, think of this: My wife is 5' 2" and I am 6' 3", so if I grab the wrong remote and jump right in the car without looking, my voice becomes very high pitched as my family package gets crushed. I am quite a ways from a Caddy dealship so any DIY friendly tips are greatly appreciated.

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By disconnecting both cables and touching them together for a few seconds ... it will discharge all of the capacitors in the car.

You may or may not...(probably will)... have to reprogram your seats and AUTO UP windows...

Sometimes they lose their settings... sometimes they don't..

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Mine does not show exact temps either, but the middle mark is labeled '220' so I figured out what the unlabeled marks were from there. Now that my CTS is back to normal it runs at a constant 200 (one mark below the middle mark) when it's warmed up.

From my understanding the aux water pump is the most likely cause of the light. I'm not sure if yours uses the same pump, but if it does Amazon is BY FAR the best price if you want the OEM GM / AC Delco (p/n: 25808860) pump: http://www.amazon.com/gp/product/B0016IDG6A/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1

The pump is very small (fits in the palm of your hand). If you are standing in front of the car, and looking down between the back of the radiator and the front of the engine, the aux water pump will be on the bottom left corner of the back of the radiator. At least that is where it is on the 2008 CTS: Edit: I just pulled up the diagram for the 2008 STS, and the pump is in the same location, they actually map this same image for both the CTS and the STS:

wMQqG7n.png

The official procedure is to drain the engine coolant completely, then replace the pump, then put new coolant in. I clamped the two hoses going to the aux water, and replaced the pump without draining the system, however I'd keep an eye on your coolant levels each day for at least a few days after that (if you do it my way) to give it enough time to work the air back out of the system and add back whatever coolant you loose during the swap. The impeller on my pump was hard to turn and had a 'gritty' feel to it - so it was for sure bad.

More random info: After removal of the old pump, of course I had to take it apart. This is a picture of 'logic board' that is built into the pump. Mine was burned. At first I thought it fried when the pump seized, but now I think it may have burned when I tried to 'test' the pump while it was still on the car. I had read you could remove the wring harness from the pump, and hook up 12v instead to the pump and listen to see if it ran. Well turns out these little pumps on our cars run at around 4v. :o At least the pump was already bad (seized) anyway!

myaOFpZ.jpg

Crystal Red Tintcoat Exterior | Shale/Brownstone Interior | 32k

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THANKS for the fast responses!!!

Texas Jim: draining the capacitors is to keep from lighting yourself up while screwing with the harness or does it actually reset the system?

davedog: "After removal of the old pump, of course I had to take it apart." WELL OF COURSE! We may be related. Did the same thing to the pump unit on our Sleep Number Bed, then watched it deflate and I got the couch for three days until the UPS truck pulled up and I forked over $280.

Seriously thank you! What I thought was the pump was something else (have no idea what yet but give me time). Yes, it is the same pump. Sitting at an idle from cold start the fan is off, turn A/C on and within a minute the fan come on, turn the A/C off, within a minute the fan goes off. Does this sound normal?

Where did you pull the diagram from? You know Marines, we do much better with pictures!

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THANKS for the fast responses!!!

Texas Jim: draining the capacitors is to keep from lighting yourself up while screwing with the harness or does it actually reset the system?

Both... :)

That's why I mentioned that you will probably have to reset your seats and window controls... and maybe even your radio stations.

But that is the SUREST WAY to force a complete system reboot on the next ignition cycle.

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