Coolant level warning - just for a second

[SouthWestern]

The coolant level warning came on permanently a few days ago - coolant level was perfect. Having read on the forum that the coolant level sensor frequently fails, we changed it. This removed the message in text on the dash/radio display, and the red warning picture that was on the little display next to the speedo.
However...
When starting the car, the error comes on briefly - no more than a second - some of the time. Sometimes only in text on the dash/radio display, sometimes the red picture as well, and sometimes not at all.
Any suggestions? Is this somehow now a stored fault?
We would like to sort this out as the car (daughter's) needs to be sold.
Thanks in advance!

 

[Pedro]

Coolant level sensor is failing common fault on all Zs only replace with a Bosch one & it should cure the fault

 

[SouthWestern]

@Pedro Just wondering if this is from personal experience of this sensor, or just a general preference for Bosch? Reason for asking is I haven't been able to find one, just Bosch temperature sensors.
I bought the this one from Amazon, it seems to get mostly 5* reviews... I guess I could try another.

 

[Pedro]

I fitted a aftermarket 1 from ebay exact part spec for my engine code & it failed within a fortnight replaced with a Bosch = No coolant level warning as per the correct part now fitted so I will only fit Bosch or PSA Citroen specified parts on mine & yes they cost more but will last longer!

 

[Nemi]

Same here, tried a few coolant level sensors from aliexpress and they failed within a month or so.

 

[SouthWestern]

Just adding that after a few days of this behaviour, the coolant level sensor seems to be working fine. I did buy another (not bosch, couldn't find one) but I am sending that back as the cheap one seems to work fine.
Almost as if the car had to learn that it had a new sensor... or needed time to forget about the fault?

 

[Mikefrank]

Just adding that after a few days of this behaviour, the coolant level sensor seems to be working fine. I did buy another (not bosch, couldn't find one) but I am sending that back as the cheap one seems to work fine.
Almost as if the car had to learn that it had a new sensor... or needed time to forget about the fault?

I bought a new one from main dealer and I’m still getting low coolant message….

 

[Pedro]

Check cap on expansion bottle is tight
The message reappearing may be the BSI needs resetting as old fault codes will be triggered by new issues even if its not cooling related

 

[Mikefrank]

I haven’t done the BSI Reset and I know it’s quite a lengthy pain to do with what’s involved…..is there an easier way?

 

[Pedro]

I haven’t done the BSI Reset and I know it’s quite a lengthy pain to do with what’s involved…..is there an easier way?

Never had to do one on mine but there is a certain knowledgeable chappie on here who has posted numerous BSI resets I assume you have cleared the Faults off the ECU although as you have changed the main culprit (sensor) Alternately this happens when you have a small system leak ? Some Peugeot owners not just with Zs have actually changed the expansion cap & its cured their issues

 

[Mikefrank]

Regarding the expansion cap I’m wondering if mines faulty….when unscrewing (engine cold no pressure build up in bottle).. it turns fairly easy then goes tight before coming off?…
Any you guys had similar?

 

[Pedro]

Regarding the expansion cap I’m wondering if mines faulty….when unscrewing (engine cold no pressure build up in bottle).. it turns fairly easy then goes tight before coming off?…
Any you guys had similar?

Look for white stains below the tank or anywhere on side of the engine mine had them & was losing small amount of coolant until I tightened the cap not losing any now but if the cap is overtightened it will not form a proper seal it unseats itself on the threads so it appear tight but its definitely not