PSM + Misfire code simultaneously

[doublegarage]

I'm confused by a fault that keeps appearing on my 2011 Cayenne S.  71,800 miles, I've owned since 70,500 with little history known before my ownership. Therefore sorting through the usual new-owner issues. 

 

I'll illustrate with an example. 

- Last night, car was running perfectly, had been fine for about 150 miles - connected Durametric and saw no codes under engine, PSM, tiptronic, AWD etc 

- this morning - 60 mile roundtrip - about 3 miles from home suddenly car feels like it's running rough, maybe on 6 or 7 cylinders, dashboard alternates between "Check Engine", "PSM Failure" and "Start-stop deactivated"

- switched car off/on - no change

- got home and read codes as follows:

  Engine:   P0305  Upper limit value exceeded

  PSM:   U112300   Databus error value received Factory Fault Code 336397    Warning Indicator On   Test Completed This Monitoring Cycle
       Test Not Failed Since Last Clear  Test Completed Since Last Clear  Not Pending DTC  Test Not Failed This Operation Cycle   Fault Active

  AWD:  293 / 125  PSM activation by PTM  Warning Indicator Off  Pending DTC   Test Failed This Operation Cycle   Fault Active

  AWD:  12656773 / C12085  Check PSM control unit fault memory content   Warning Indicator Off  Test Completed This Monitoring Cycle  Test Failed Since Last Clear
       Test Completed Since Last Clear   Pending DTC   Test Failed This Operation Cycle   Fault Active

 

 

So the P0305 is misfire on cylinder 5, I get that.  Back home the car was idling and running roughly when I cleared that code and it instantly smoothed out.   Does it shut down cyl5 when a misfire is detected more than some number of times?  Normally I'd pull that plug and inspect/replace that coil etc, but the fact that it happens in conjunction with all the PSM warnings has me suspicious. 

 

Can anyone throw some light on the PSM and AWD faults?  Searching for those numbers hasn't helped yet - still searching, but thought I'd ask here too. 

 

Note, clearing these codes cleans everything up, no codes return and all runs perfectly - until next time (3 cycles so far)

 

-Richard

Santa Cruz, CA

2011 Porsche Cayenne S

 

 

[Loren]

 

When I see random seemingly unrelated intermittent electronic faults on a Cayenne the first two things I think of are battery and grounds.

These cars are really susceptible to a weak battery or corrosion on the main ground cables. I would check those first.

[doublegarage]

Thanks Loren - the car starts like a champ, really cranks over fast, so it hadn't occurred to me it could be the battery.  But I see what you mean.  I'll take a look at the ground cables, then change the battery.

-Richard

[swpender]

My 2011 Turbo has 80k now and the triple fault started a year and 10k miles ago, when it was still under CPO warranty. I guess the dealer service departments are incentivized to do the most expensive fix, so when i took it in, they replaced the coils on misfiring cylinders. Now that the warranty is expired, i sure hope you are right on the battery issue since it's acting up again.

[doublegarage]

2 hours ago, swpender said:

My 2011 Turbo has 80k now and the triple fault started a year and 10k miles ago, when it was still under CPO warranty. I guess the dealer service departments are incentivized to do the most expensive fix, so when i took it in, they replaced the coils on misfiring cylinders. Now that the warranty is expired, i sure hope you are right on the battery issue since it's acting up again.

Hello, and thanks for the reply.   

On another forum suggested the bad-coil idea - and there was one code which suggested a misfire on cylinder 5 - that cylinder was therefore shutting down and the car running rough until I cleared the code.  I changed that single coil, and the car hasn't had the problem since - therefore I changed the other 7 coils. 

It seems that changing coils should be a service item - everyone who's had the problem sees them failing at about 70k miles like mine. 

 

Thanks, 

 

-Richard

[swpender]

I changed out all of mine as well. When I dropped my '11 Turbo off at my garage, the service manager said that were going to send a camera into the cylinders after pulling the plugs. My explanation of the fault codes he told me the camera is to check for scoring. He's told 2 other '11 turbo owners in the last month that they need an engine replacement. Porsche isn't helping out either. I was quite happy to hear that my cylinders were unscored.

[Tom M]

I just had this happen to my 2011 CS w/95,800 miles yesterday on the way home. My first thought, when I started seeing all the warnings pop up, was the variocam bolts let go. Fortunately it smoothed back out after I pulled off. I read/cleared the codes with my Durametric when I got home and all was fine on the way into work this morning.

 

Based on the research I'm betting on it being a coil starting to go bad. The local dealer wants twice as much as mail order so I'm hoping things will last until a replacement coil gets here in a few days.

[doublegarage]

1 hour ago, Tom M said:

Based on the research I'm betting on it being a coil starting to go bad. The local dealer wants twice as much as mail order so I'm hoping things will last until a replacement coil gets here in a few days.

 

Yes I bought all 8 from Sunset Porsche.  The problem has never re-occurred. Good luck, 

 

-Richard

[deilenberger]

My suggestion is - if one coil is on it's way out - all it's little sisters and brothers are just waiting for you to replace the one and then they'll start failing.  Makes sense - the coils die because of heat - and too much current pushed through too small a coil (causing some of the heat) - and they live in identical conditions. When one goes - replace all of them.  Throw a few of the old ready-to-fail ones in the spare tire well to invoke Eilenberger's Law of Spares: "You'll never need the part you have.."

[Loren]

If measure each coils resistance (with an ohm meter) you may find one coil that is vastly different. That coil is likely the bad one.

[Sweet35th]

On ‎8‎/‎5‎/‎2017 at 4:23 PM, doublegarage said:

I'm confused by a fault that keeps appearing on my 2011 Cayenne S.  71,800 miles, I've owned since 70,500 with little history known before my ownership. Therefore sorting through the usual new-owner issues. 

 

I'll illustrate with an example. 

- Last night, car was running perfectly, had been fine for about 150 miles - connected Durametric and saw no codes under engine, PSM, tiptronic, AWD etc 

- this morning - 60 mile roundtrip - about 3 miles from home suddenly car feels like it's running rough, maybe on 6 or 7 cylinders, dashboard alternates between "Check Engine", "PSM Failure" and "Start-stop deactivated"

- switched car off/on - no change

- got home and read codes as follows:

  Engine:   P0305  Upper limit value exceeded

  PSM:   U112300   Databus error value received Factory Fault Code 336397    Warning Indicator On   Test Completed This Monitoring Cycle
       Test Not Failed Since Last Clear  Test Completed Since Last Clear  Not Pending DTC  Test Not Failed This Operation Cycle   Fault Active

  AWD:  293 / 125  PSM activation by PTM  Warning Indicator Off  Pending DTC   Test Failed This Operation Cycle   Fault Active

  AWD:  12656773 / C12085  Check PSM control unit fault memory content   Warning Indicator Off  Test Completed This Monitoring Cycle  Test Failed Since Last Clear
       Test Completed Since Last Clear   Pending DTC   Test Failed This Operation Cycle   Fault Active

 

 

So the P0305 is misfire on cylinder 5, I get that.  Back home the car was idling and running roughly when I cleared that code and it instantly smoothed out.   Does it shut down cyl5 when a misfire is detected more than some number of times?  Normally I'd pull that plug and inspect/replace that coil etc, but the fact that it happens in conjunction with all the PSM warnings has me suspicious. 

 

Can anyone throw some light on the PSM and AWD faults?  Searching for those numbers hasn't helped yet - still searching, but thought I'd ask here too. 

 

Note, clearing these codes cleans everything up, no codes return and all runs perfectly - until next time (3 cycles so far)

 

-Richard

Santa Cruz, CA

2011 Porsche Cayenne S

 

 

 

Richard,

 

   I recently had the exact same concern on my wifes 2011 Cayenne S with 63k on it.       Cylinder 8 misfire (P0308)  and would come up with PSM failure, auto stop disabled, abs, 4wd system, etcetera.    

 

   I found the spark plugs were original, and I had 4 cracked ignition coils.   I replaced all spark plugs and the 4 cracked coils.    This resolved both concerns.         My suspicion is that RFI from the cracked coils is likely occurring, which can interfere with any Hrtz or Voltage signal from other sensors, and can simply ***** off multiple modules.  

 

    I see this in the dealership all the time on other makes of vehicles (been a Ford senior master tech for 20 years now).   Its generally hard to diagnose, but typically leads to ignition or charging system issues causing the RFI interference .     Since you are throwing a misfire code (as was I), it is most likely that is the cause.   I would repair the condition, clear all codes and recheck.          

 

 My wife and I have since put on another 4000 miles with no issues.   We are also replacing the remaining 4 coils as a precautionary measure.     Replacing the plugs and coils is a very quick and easy task, with the only special tool needed is an inverted torx socket.    The whole job should not take much more than an hour.

 

[swpender]

Richard, My problems were resolved by changing out all coils and plugs. I would highly recommend replacing the full line-up. Steve