Hello,

Son's 2013 manual is overheating - and apparently has been doing so for some time... kids.

Q: The dash temperature readings appear to be accurate, starting cold and increasing as the engine warms up, reaching and maintaining an indicated 90 when moving.

Is the temperature sensor providing the dash display the only temp sensor involved, so I can discount the temp sensor as a probable cause?

Son no longer lives at home and so my access to car is limited. Thermostats, fan, relays and associated wiring have yet to be checked.

All advice gratefully received.

First check is the Anti Freeze (Summer coolant / anti corrosion.)

Is it at the correct strength and has it been changed in the past 12 years.

It is not just near water being run from having been topped up with just H20 is it?

Reasonably confident that the coolant is reasonably recent and to spec. Car was purchased new for my wife and then "gifted/nicked" by Sprog 1.

That written, it may well be worth a renewal - but I don't think it is a cause of the current issues: expansion sphere looked suitably pink when I last looked a couple of days ago.

Shameless bump of my own thread...

Original Q: Is the temperature sensor providing the dash display the only temp sensor involved in the cooling system, so I can discount the temp sensor as a probable cause of overheating?

Thanks.

Yes, probably the only temperature sensor, communicating initially with engine ECU, but then that data being shared to other modules like the dash panel.

There is often a thermoswitch, in or near the radiator that controls the radiator fans, but gives no numerical temperature to any modules.

I can look up more info about your car if you share reg or VIN. But not just now, about to be driving for a while.

47 minutes ago, Breezy_Pete said:

Yes, probably the only temperature sensor, communicating initially with engine ECU, but then that data being shared to other modules like the dash panel.

There is often a thermoswitch, in or near the radiator that controls the radiator fans, but gives no numerical temperature to any modules.

Hello Pete, thanks for the information - and the offer.
Enjoy your drive 😉

Home now, so could look stuff up.

2 hours ago, Breezy_Pete said:

There is often a thermoswitch, in or near the radiator that controls the radiator fans, but gives no numerical temperature to any modules.

Hello Pete,
I have not made enough posts to be able to message you directly, and am reluctant to put VIN / REG in a public forum.

If it provides sufficient info, the beast is a Citigo Sport, first registered date July 2013

V5 lists the "Variant" as ABCHYA, which I think identifies it as a 60HP manual, which indeed it is.

Thanks for the info above re a thermoswitch. This has now moved to suspect No.1 in my list for my amateur diagnostics... 🙃

I'll start a message exchange with you, you'll be able to reply. 🙂

If the coolant temperature gauge is a swing needle dial then it is design to show 90c and steadily remain there even though in reality the temperature could be within a range below and above 90c. Above or below that range the needle with be lower or higher than 90c.

I might be misunderstanding but if the coolant gauge needle is reaching and maintaining an indicated 90 when moving what is meant by overheat - or is the coolant gauge needle showing well above 90c.

Some quick thoughts

if the coolant level is at a good level in the filler expansion tank when the engine is cold is the pressure cap fulling closed and sealing

what's the oil level on the dip stick

are any of the brakes dragging/catching

no exhaust partial blockages

any warning messages, lights or error codes?

does the call overheat all the time or at certain times?

ETA: has any work been done on the car or parts fitted a bit before the overheating started?

Thanks to you both for replying - Pete, I have responded to your message.

Hello Nigel, as the car no longer lives here full time I am an unreliable source of information.

As I understand it, the car overheats if stationary in traffic for an undefined period.

The temperature as reported on the dash is via a selection in the LCD display; there is no old school gauge.
I serviced the car (engine oil, oil filter, air filter, cabin filter, plugs) just prior to MOT in June, at which the sole advisory was brake disc wear.

We had a visit from Sprog 1 this week, which is when the overheating was mentioned in passing. I had a brief look and oil and coolant levels are as they should be.

No lights that I am aware of. When I can gain access to the car, will try my Torque app to see if I can read for codes.

Edited 15 August, 202515 Aug by MobileChicane

One question that's puzzling me slightly.

If the indicated temperature is 90, what makes you think the engine is overheating? Is there loss of coolant? Some external temperature measurement method?

Thanks for the information you provided, Pete.

I am informed that if stationary with the engine running then the temperature will rise - 115 has been seen. At that point the technique employed is to turn the cabin heater to max and try and dump heat into the car - fun times!

No loss of coolant; level looks good in expansion sphere.

Partial response - sorry.

Unclear to me if the rad fan is kicking in; I suspect that it is not.

Unclear when I will get time with the car, but I think that the thermostatic sensor for the rad fan has to be my new prime suspect.

Is the 115 definitely coolant temperature rather than oil temperature?

30 minutes ago, Breezy_Pete said:

Is the 115 definitely coolant temperature rather than oil temperature?

In the 2013 model the MFD does not provide an option to display oil temperature, only coolant temperature.

Have downloaded the owners manual to confirm this.

I would certainly expect radiator fan action in that case. May be able to offer fuse info tomorrow, but hopefully covered in owner's manual.

Yes, found a couple of threads on here which detail the fuses involved.

Thanks again for your time, Pete. The details you provided re the thermostatic sensor for the rad fan have given me a great pointer.

If he's stationary in traffic before he puts the heater blower on get him to turn off all over noises (infotainment, TwatNav, phone, etc.) and listen for the rad cooling fan(not) cutting in and you'll have more of an idea.

As well as having the heater on he could reduce the load on the engine but not running stuff like air-con and having blower on full, it won't stop the car getting warm but it might help keep it a bit lower for a bit longer.

I think part of your problem is that you done the service rather than previously showing and letting your son do the service as that way he'd learn more about the car and not have this long term issue, ya gotta blame the parents. 😁 When my mates youngster two lads had their runabout they didn't know how to put the spare wheel on and had to get the help of a mechanic at a nearby garage, they were strapping, healthy lads (footballers) and the Daewoo Matiz had small wheels with three wheel nuts to each wheel. One later had an overheating car, you could smell the heat, the fact there was barely a drip of oil on the end of the dipstick didn't help.

Thanks Nigel - will ask for further diagnostic info.

Parents are always to blame 😁 In his defence, son is automotively quite savvy. My mid-life crisis was a Caterham, which he helped me tinker with mechanically. He can pop the bonnet and knows what he is looking at with a reasonable level of detail. Tyre changing is not an issue, etc.

Key reason I am involved is that he and his fiancé have a first-floor flat with assigned car parking spaces, but no real room to work on the car without potentially getting in other people's way and no power source anywhere near.

Since the car has A/C, a quick and easy test of radiator fan operation is to run engine and demand minimum temperature with A/C switched on, bonnet open. That's assuming the A/C is actually operable/cooling successfully.

At the sort of ambient temperatures we currently have, the radiator fan should start up at low speed within a pretty short time. Keep fingers away while waiting to see!

I was just looking at wiring info, and the resistor for low speed fan operation appears not to be within the fan motor, but instead at a 3-way connector pair where 3 wires become 2.

When the resistors were housed inside the fan motor assembly they were a bit infamous for failing, leaving only high speed operation thereafter.

Edited 16 August, 202516 Aug by Breezy_Pete

Unless he's mains recharging the battery he should be alright without mains electric as for getting in other people's way that another matter but to me it's never any fun farting about with cars even if you have the loan of a mate's garage but a multimeter and scan tool are battery powered and you don't even need to check battery charge on hand tools (though I find the can-be-arsed supply for can be very low many times).

Breezy_Pete's yer man for the electrics and their details. The varying small or tiny wunderbar less-than-fantastic plastic wire connectors can be a fiddly PITA and sometimes difficult to power items, that can be, direct from leads connections to 12V battery for direct power/earth testing for yay/nay confirmation of working, which is where an appropriate scan tool can be useful for activation test.

Blimey you had a real crisis Caterham instead of Westie! 😁

Edited 16 August, 202516 Aug by nta16
typos

@MobileChicane I'm looking at wiring info for the fan control module, trying and failing to see how the radiator thermoswitch is involved on an A/C equipped Citigo of this vintage.

You may find that either there physically isn't one, or that it isn't wired up. Not sure. Parts catalogue suggests it's there though.

Hello Pete,
Noted re your last above. I have risked the £8.68 and ordered a radiator thermoswitch from ebay just as a precaution - livin' life on the edge!