C3 Fault Codes

[sstef]

Hello,

Vehicle: Citroen C3 2006 1.4HDi 68hp

I’m dealing with two fault codes: P0692 and P0495.

Symptoms:
The overheat warning light keeps blinking constantly, even with the engine OFF.
Sometimes there’s also a warning beep.
The A/C blows cold air for a few minutes, then switches to ambient/warm air, then back to cold again in a repeating cycle.

What I’ve checked so far:
Replaced the coolant temperature sensor.
Checked the fan control relay and it appears to be working properly.
Coolant level is normal.

I’m trying to figure out what else could cause these symptoms.

[mickthemaverick]

You may get an idea or two at:

https://www.engine-codes.com/p0692.html

[Sloppysod]

Can't help you directly, you say the overheating light is blinking, but is the car actually overheating, does your model have a temperature gauge?
Have a read through this.
viewtopic.php?t=62604

[Maznaatesh]

Can't help you directly, you say the overheating light is blinking, but is the car actually overheating, does your model have a temperature gauge?
Have a read through this.
viewtopic.php?t=62604

Hi,
It’s not actually overheating (the temperature gauge shows the correct reading), only the top light is blinking, exactly like in the topic you linked. I tried changing the coolant temp sensor as mentioned there, but unfortunately it didn’t resolve the issue.

[Sloppysod]

As I said i can't help directly, but both codes seem to relate to the cooling fan or its circuitry. The car is obviously sensing an issue somewhere.
Does the fan start (test my getting the engine hot without driving)? If not a common area to check is both temperature sensors or the fan relay.

[ozvtr]

The blinking LED is a failure of the coolant level sensor in the expansion tank. If the coolant level is OK then the sensor is faulty. Only diesel C3s have this sensor.

To test if the fan circuit is working, (with the engine running) disconnect the green coolant temperature sensor electrical connector. The fan should come on fully within 10 seconds. If it doesn't come on then you have a problem. Failure of the fan circuit usually turns all the temperature LEDs on?!

If there is a problem with the radiator fan circuit the A/C wont work. It shouldn't work at all, so I cant explain why it comes on then goes off. Fix the radiator fan circuit problem before you start worrying about the A/C.

I can only postulate from the available data that the "low speed fan" (radiator) circuit is working but the "high speed fan" circuit is not. Otherwise, with no radiator fan, your engine should have boiled over by now!
The low speed fan might not be enough to cool the A/C condenser and the "high side" pressure gets too high. The A/C stops working until the high side pressure comes down. I dunno, just a guess.

[sstef]

The blinking LED is a failure of the coolant level sensor in the expansion tank. If the coolant level is OK then the sensor is faulty. Only diesel C3s have this sensor.

To test if the fan circuit is working, (with the engine running) disconnect the green coolant temperature sensor electrical connector. The fan should come on fully within 10 seconds. If it doesn't come on then you have a problem. Failure of the fan circuit usually turns all the temperature LEDs on?!

If there is a problem with the radiator fan circuit the A/C wont work. It shouldn't work at all, so I cant explain why it comes on then goes off. Fix the radiator fan circuit problem before you start worrying about the A/C.

I can only postulate from the available data that the "low speed fan" (radiator) circuit is working but the "high speed fan" circuit is not. Otherwise, with no radiator fan, your engine should have boiled over by now!
The low speed fan might not be enough to cool the A/C condenser and the "high side" pressure gets too high. The A/C stops working until the high side pressure comes down. I dunno, just a guess.

I'm pretty sure your guess is correct. I tried the test, the fan turns on (the problem is, I think it turns on at the LOW speed) as soon as I disconnect the coolant temperature sensor and the temperature gauge shoots up to the top. I will try changing the coolant level sensor next, is it possible that this is connected to the LOW/HIGH speed issue or should I look somewhere else for that?

[ozvtr]

I will try changing the coolant level sensor next, is it possible that this is connected to the LOW/HIGH speed issue or should I look somewhere else for that?

Is the coolant level sensor responsible for the radiator fan problem? No.
The Peugeot/Citroen radiator fan controllers are notoriously unreliable. With the green temp sensor disconnected, the radiator fan should go to full speed. You'll know the fan will be at full speed, it will be loud and move a lot of air!
There are a lot of variations to the fan controllers, but typically they are a removable module in the fan shroud. They can be identified by a coil of wire under a metal cover that has holes in it. I would assume the module has two electrical connectors. One will have (perhaps) three small contacts and the other will have two big contacts. Again the modules come in all shapes and sizes so I couldn't tell you exactly what yours looks like.

[sstef]

UPDATE:

I swapped out the coolant level sensor in the expansion tank, and that fixed the constant beeping and the blinking warning light.

As for the low/high-speed fan issue and the A/C cycling, turned out to be the relay after all. I replaced it, and now the fan turns to high speed when it should, and the A/C is blowing cold consistently again.

Thanks for the help, everyone!

[mickthemaverick]

Glad you've got it sorted Well done!!