cooling fan running all the time

[crawfordc]

help needed please, my 2006 Expert2.0HDI is misbehaving, when I start up the van the temperature gauge doesn't move instead I have the red warning light, flashing stop light and engine fault light showing on the dashboard, and the cooling fan runs at high speed. I've replaced the temperature sensor that is on the side of the engine above the gearbox thinking that was the problem but alas no, I've also checked the the wiring for breaks and found none, checked for continuity between the sensor and Ecu that is ok, fault code Im getting with peugeot planet is P0115 Coolant temperature signal my vin number is VF3**************[VIN obfuscated, can be read by forum staff]. RPO number is 682.

[Arkis]

If you are 100% correct that all the wiring is good, the sensor is new and both old and new are not registering any data, then it will be ECU malfunction.
Also there might be 2 temperature sensors. Some engines from that age had two sensors. One for ECU and one for gauges. Unfortunatelly I can't see the VIN so I can't check it. But if you connect diagnostic tool and check live data and there is no temperature reading, then you probably have only one sensor (or two and both are broken).

[crawfordc]

If you are 100% correct that all the wiring is good, the sensor is new and both old and new are not registering any data, then it will be ECU malfunction.
Also there might be 2 temperature sensors. Some engines from that age had two sensors. One for ECU and one for gauges. Unfortunatelly I can't see the VIN so I can't check it. But if you connect diagnostic tool and check live data and there is no temperature reading, then you probably have only one sensor (or two and both are broken).

Arkis you may well may right that my van has 2 sensors as live data does indeed show the engine temperature , would you know whereabouts it is and a part number for the other sensor

[Ady2021]

Check there is no water in the electrical plugs that go into the ECU. Mine did the same and it was water in the ECU which had to be sent off to be repaired. Warning - there is only one decent ECU repair place in the UK. I sent mine to about 5 places before I found the one place that could actually repair it.

[crawfordc]

Check there is no water in the electrical plugs that go into the ECU. Mine did the same and it was water in the ECU which had to be sent off to be repaired. Warning - there is only one decent ECU repair place in the UK. I sent mine to about 5 places before I found the one place that could actually repair it.

ive had the engine wiring harness opened and disconnected from the ecu while i was looking for breaks int the wiring

[Arkis]

According to the microfiche, you have only one temperature sensor. Original number 1338C1.

I have had similar problem on my 206 where the gauges were not working, but on live data it showed correct data, in the end the gauge motor in the dashboard was dead so I had to resolder it for a new one. But there were no flashing warnings on the dash. I think the dead gauge motor will not trigger any faults or warnings on the dash. You said you have check engine light on. What does the code says?

[wheeler]

Service box shows 2 temp sensors for this vehicle. A 3 pin one part number 1338A6 and a 2 pin one part number 1338C1.

[Arkis]

I don't know if I am blind, but I can see only one.

[wheeler]

The one you can see is listed under cooling system, There is another one listed under engine management.

[Arkis]

You're absolutely right. Thanks for correcting me.

[crawfordc]

thanks guys, for clarifying that my van has 2 sensors, guess i'm going play hunt the sensors

[wurlycorner]

Warning - there is only one decent ECU repair place in the UK. I sent mine to about 5 places before I found the one place that could actually repair it.

Hi Andy,
Just curious - which one did you use and find was successful, in the end?

[crawfordc]

The one you can see is listed under cooling system, There is another one listed under engine management.

think I've found it but not where it shows on the drawing, on my engine its on the rear r/h looking from the front of the van, and looks like part no 9802028080

[crawfordc]

look's like is uses the oil temperature to show the engine temperature going by the circuit diagram i've found, or am i barking up the wrong tree with this sensor. code i'm getting is P0115 short circuit to positive, live data shows coolant temperature but the temperature shows nothing except the overheat warning lamp, I've also got the flashing stop light and engine fault light

[Arkis]

P0115 is pointing in the right direction. It means there is error in temperature sensor circuit. It might be in the wiring, connectors or ECU.
If you are not sure which sensor is for what, just read live data and unplug one sensor. If live data is still reading, the other sensor is for ECU/Diagnostic purposes. This way you can see what circuit is broken. Then you have to try continuity in the wiring. I would start with grounding because it's easier to find and is usually the culprit.