“Engine must be running”

[Micky 32]

Hi all. An unusual problem the past week. I noticed the start stop isn’t working too well. The message i keep getting is “ engine must be running”

 

The problem is that i only ever see that message when the car is going through a regen. The car isn’t going through a regen. So what could be causing this? If it was the battery wouldn’t i be getting “ power consumption too high”? Or can a bad battery cause the other message also?

[Warrior193]

Hello Micky, it is likely to be something like the requested cabin temperature (on AC) is not down/up to setpoint, there are quite a few parameters that will inhibit auto stop/start - one I see now and then is 'windscreen may fog' - I wouldn't rule out a battery problem though, are you able to test it?

[Micky 32]

29 minutes ago, Warrior193 said:

Hello Micky, it is likely to be something like the requested cabin temperature (on AC) is not down/up to setpoint, there are quite a few parameters that will inhibit auto stop/start - one I see now and then is 'windscreen may fog' - I wouldn't rule out a battery problem though, are you able to test it?

No the air conditioning set as I normally have it. To be fair the battery isn’t 100%. 6.5 years old. However when the battery is low i usually get the power consumption is high message, never the engine must be running message. I only ever see that during a regen.

[Warrior193]

I have seen the 'engine must be running' message a few times on my TSI (obviously not for regens) - I usually connected it to cabin or engine coolant temperature. Try a recharge and get the battery condition tested. 

[Micky 32]

Usually i get a specific message about the air conditioning when cabin temps aren’t met.

 

no, this is new. After 186,000 miles i can’ tell she’s trying to tell me something lol

 

I have a battery tester. It currently is producing 380 amps EN. Battery AGM is rated at 680 amps EN. 

[Warrior193]

15 minutes ago, Micky 32 said:

Usually i get a specific message about the air conditioning when cabin temps aren’t met.

 

no, this is new. After 186,000 miles i can’ tell she’s trying to tell me something lol

 

I have a battery tester. It currently is producing 380 amps EN. Battery AGM is rated at 680 amps EN. 

Is that test throwing up a 'replace battery' message?

I have found testing my Octavia (Moll, EFB) battery against two standards (DIN & SAE) gives slightly different readings - but appears to give a reasonable idea of condition.   

[Micky 32]

Yep. Using a topdon. I have been watching it decline over the past 3 years. When the reading drops below 430 amps on a 680 battery it says “ replace “. It has been telling me to replace intermittently over the past 3 years. However during the summer on hot days I miraculously have a “ Good Battery”.

 

i think these testers condemn a battery too soon. They only give you an idea of the batteries health. Results can differ a lot with temperature.

 

My battery is now reading 375-380 amps with a replace message at 15 degrees C . Sometimes the starter does sound sluggish and in cold weather i do get errors beeping on the dash on a cold morning start. The funny thing is for  most part the start stop works fine. But last winter it was limited. It worked fine all summer.

 

From my experience AGM’s die a very slow death. 

Edited 20 September, 2023 by Micky 32

[Warrior193]

22 hours ago, Micky 32 said:

Yep. Using a topdon. I have been watching it decline over the past 3 years. When the reading drops below 430 amps on a 680 battery it says “ replace “. It has been telling me to replace intermittently over the past 3 years. However during the summer on hot days I miraculously have a “ Good Battery”.

 

i think these testers condemn a battery too soon. They only give you an idea of the batteries health. Results can differ a lot with temperature.

 

My battery is now reading 375-380 amps with a replace message at 15 degrees C . Sometimes the starter does sound sluggish and in cold weather i do get errors beeping on the dash on a cold morning start. The funny thing is for  most part the start stop works fine. But last winter it was limited. It worked fine all summer.

 

From my experience AGM’s die a very slow death. 

A cold winter this year could very well push it over the edge. I'd seriously consider replacing it - if you do, make sure to get it adapted in the settings.

[Warrior193]

@Micky 32 another thought - do you run a lot of fairly short trips? if so, does your maintenance schedule include an occasional full recharge?

The 'smart' alternators fitted to these vehicles rarely allow the battery to charge above 75%. 

[Micky 32]

On 21/09/2023 at 17:40, Warrior193 said:

@Micky 32 another thought - do you run a lot of fairly short trips? if so, does your maintenance schedule include an occasional full recharge?

The 'smart' alternators fitted to these vehicles rarely allow the battery to charge above 75%. 

No, the car gets good long trips. I have nearly 190,000 miles (2017). I have a battery monitor and the voltage is good. However the first cold morning this year the car just about started. It went into limp mode when it started. The low cranking activated a low fuel rail pressure code.

[SurreyJohn]

The performance of the battery is temperature dependent, seems to me has limped on satisfactory during warmer summer months, but the colder weather is meaning new battery is required.

 

@Micky 32 when you say you checked battery, was that in a warm garage at nearer +20c, or in cold morning parked outside at nearer 0c.  
Bet you will get different readings.  The first reading is pointless if park car outside

[numskull]

Must be the battery. 
EDIT - SJ just beat me to it! 😂

Edited 17 October, 2023 by numskull

[J.R.]

Re the electronic battery testers, it sounds like at least 3 of us have them.

 

I have found that the battery has to be disconnected from the vehicle otherwise it will give highly pessimist readings even with a brand new fully charged battery.

 

I have also noticed the difference in the DIN/SAE readings but remember they are different testing regimes so the same new battery would give a different AH output according to which test method was used.

 

The temperature should not be an issue, the testers report the off load voltage and temperature and make corrections for them, without that every battery on a stop-start car charged to only 75% would be condemned by the tester.

Edited 17 October, 2023 by J.R.

[Micky 32]

5 hours ago, SurreyJohn said:

The performance of the battery is temperature dependent, seems to me has limped on satisfactory during warmer summer months, but the colder weather is meaning new battery is required.

 

@Micky 32 when you say you checked battery, was that in a warm garage at nearer +20c, or in cold morning parked outside at nearer 0c.  
Bet you will get different readings.  The first reading is pointless if park car outside

Correct. The readings are quite different with temperature. When it was 20 plus degrees i was getting a reading of about 480 amps and a “ good battery”. When i tested it the other morning at 9 degrees it read 325 amps and “replace”. However the battery is toast because it just about started the other morning so i think it certainly has less than 480 amps.

  
I have a intermittent issue with “ keyless access system faulty”.  “engine must be running” only comes up when that fault occurs so it’s related to the keyless fault.. Both faults seem to have disappeared.

 

Edited 17 October, 2023 by Micky 32

[SurreyJohn]

3 hours ago, Micky 32 said:

I have an intermittent issue with “ keyless access system faulty”.  “engine must be running” only comes up when that fault occurs so it’s related to the keyless fault.. Both faults seem to have disappeared.

Don't bother to look for other fault until battery is fixed, weak batteries can throw up all sorts of spurious messages that sort themselves out when battery voltage is back to normal

[Warrior193]

5 hours ago, J.R. said:

Re the electronic battery testers, it sounds like at least 3 of us have them.

 

I have found that the battery has to be disconnected from the vehicle otherwise it will give highly pessimist readings even with a brand new fully charged battery.

 

I have also noticed the difference in the DIN/SAE readings but remember they are different testing regimes so the same new battery would give a different AH output according to which test method was used.

 

The temperature should not be an issue, the testers report the off load voltage and temperature and make corrections for them, without that every battery on a stop-start car charged to only 75% would be condemned by the tester.

I have found that you can get a reasonable test result with the battery connected - provided you allow all the modules time to go to sleep - this seems to happen on my Octavia after 5-10 mins at most.

I would prefer an educated pessimistic battery condition reading any day.

[J.R.]

2 hours ago, Warrior193 said:

I would prefer an educated pessimistic battery condition reading any day.

 

Agreed, I use mine more as a comparator.

 

Waiting for the modules to shut down will not work unless you have fooled the bonnet open sensor, mine no longer works so one less problem 👍

 

However I have found that even doing that and waiting the test results are significantly lower than when I disconnect the battery terminal, the alarm and central locking reciever modules are always active, their resistance must throw the test measurement.

[Micky 32]

6 hours ago, SurreyJohn said:

Don't bother to look for other fault until battery is fixed, weak batteries can throw up all sorts of spurious messages that sort themselves out when battery voltage is back to normal

Yep i know that. But I’m fairly sure i have an actual keyless fault. It was happening in warm weather and according to my battery monitor voltages were ok when the fault was happening.

Edited 17 October, 2023 by Micky 32