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Discussion Starter #1

I'm a recent owner of a 2009 2.8 CRD and love the car. However I now have a problem with the coolant temp sensor as told by garage.


Sensor has been replaced twice with genuine part and also non genuine. The live data shows the temperature to be stable when running then for no apparent reason data shown 140 Cecius for a few seconds then returns to the actual temp of around 80. When it is unplugged it shows a stable -40c which i'm led to believe is correct. Wires have been checked visually and cannot see any evidence of chaffing.

Garage cannot find any wiring diagrams for this engine so is unable to carry out more tests without going into huge expense.

I have searched the forum and cannot find a similar problem. Does anyone have/had this issue and where can i find the diagram so I can supply to the garage?

Any help is greatly appreciated.

Thank you all!

Super Moderator
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P0117 - OBD-II Trouble Code
Our automotive experts have put together the following information about the P0117 diagnostic trouble code. We've provided the common symptoms that occur when this code is set along with the frequent repairs that address the issues related to the P0117 code.

What Does P0117 Code Mean?

OBD-II Code P0117 is defined as a Engine Coolant Temperature Circuit Low Input

What does Mean?
The Engine Coolant Temperature Sensor measures the rise and fall of the Engine Coolant Temperature. This provides critical data needed for the Powertrain Control Module (PCM) to control the Air Fuel Ratio, the Ignition Spark Timing, the cooling fans, and many components of the Emissions Control Systems. The Engine Coolant Temperature Sensor converts the coolant temperature into a voltage that is high when the engine is cold and low as the engine warms up.

Code P0117 indicates a low voltage input from the Coolant Temperature Circuit to the PCM.

P0117 Symptoms

Check Engine Light will illuminate
In many cases, no abnormal symptoms may be noticed
In some cases, the engine may be hard starting and/or get poor fuel economy

Common Problems That Trigger the P0117 Code

Defective Engine Coolant Temperature Sensor
Rusty and/or corroded Engine Coolant
Faulty or corroded Engine Coolant Temperature wiring or connections

Common Misdiagnoses

Engine Coolant Temperature Sensor is replaced when the real cause is rusty coolant
Engine Coolant Temperature Sensor is replaced when the real cause is a poor connection or chafed wiring
Engine Coolant Temperature Sensor is replaced when the real problem is in the Cooling System

Polluting Gases Expelled

HCs (Hydrocarbons): Unburned droplets of raw fuel that smell, affect breathing, and contribute to smog
CO (Carbon Monoxide): Partially burned fuel that is an odorless and deadly poisonous gas
NOX (Oxides of Nitrogen): One of the two ingredients that, when exposed to sunlight, cause smog

P0117 Diagnostic Theory for Shops and Technicians

When diagnosing a P0117 code, it is important to record the freeze frame information and then to duplicate the code setting conditions with a test drive while paying close attention to engine load, throttle position, RPM, and road speed on a data streaming scan tool. As you drive the vehicle, compare these values to the Coolant Temperature Sensor PID or parameter ID. The Coolant Temperature Sensor voltage values should rise and fall with changes in engine temperature. Compare the Engine Coolant Temperature or ECT readings to the Intake Air Temperature Sensor readings, as they should move in tandem with each other. However, the Engine Coolant Temperature sensor will have a much higher temperature range.

Check the ECT sensor connector with the key on and the engine off. There needs to be a steady 5 volt reference voltage and a very good ground. Find and use the proper engine performance wiring diagram to discern the proper color and position of these wires in the connector.

It never hurts to do a key on-engine off voltage output test of the ECT sensor. Typically, I CAREFULLY use a heat gun to raise the temperature of the area around the sensor and study the change in values of the Coolant Temperature Sensor circuit. It's important to use the scan tool data stream as this will verify the ECT harness and connections.


Super Moderator
23,457 Posts
Sorry Nitrolover1, NOT an engine sold in the USA so not much help here. Have you tried resetting the vehicle computer by disconnecting the battery?

One wire is a 5 volt reference from PCM (Powertrain Control Module) and the other is a ground supplied from PCM.

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