Ford Focus Cylinder Head Temperature Sensor?

Cylinder Head Temperature Sensor
OPERATION
REMOVAL & INSTALLATION
TESTING
Temperature sensor testing vaules

Details are as follows :----

Operation

The CHT measures the metal temperature. The CHT sensor can provide complete engine temperature information and can be used to infer coolant temperature. If the CHT sensor conveys an overheating condition to the PCM, the PCM would then initiate a fail-safe cooling strategy based on information from the CHT sensor. A cooling system failure such as low coolant or coolant loss could cause an overheating condition. As a result, damage to major engine components could occur. Using both the CHT sensor and fail-safe cooling strategy, the PCM prevents damage by allowing air cooling of the engine and limp home capability.

Removal & Installation

1. Disconnect the battery ground cable.
2. Pull back the cylinder head temperature (CHT) sensor cover and disconnect the electrical connector.
3. Remove and discard the CHT sensor.
4. To install, reverse the removal procedure. 
   
   
   

   Fig. Removing the CHT sensor

Testing

1. With the key in OFF position and the CHT sensor connector disconnected, measure the resistance between the sensor pins.
2. Normal resistance is related to engine temperature. See the chart for normal resistance readings.

CYLINDER HEAD TEMPERATURE SENSOR EXPECTED VALUES
Temperature	CHT Sensor Values
°C	°F	Cold End (volts)	Hot End (volts)	Resistance (K ohms)
0	32	4.14	-	96.255
10	50	3.73	-	59.175
20	68	3.26	-	37.387
30	86	2.74	-	24.215
40	104	2.23	-	16.043
50	122	1.76	-	10.85
60	140	1.36	-	7.487
70	158	1.04	-	5.268
80	176	0.79	3.99	3.775
85	185	0.69	3.86	3.215
90	194	0.60	3.71	2.75
95	203	0.53	3.56	2.361
100	212	0.46	3.41	2.034
110	230	-	3.07	1.523
120	248	-	2.74	1.155
130	266	-	2.41	0.8866
140	284	-	2.10	0.6891
150	302	-	1.81	0.5417
160	320	-	1.55	0.4301
170	338	-	1.33	0.3449
180	356	-	1.13	0.2791
190	374	-	0.96	0.2278
200	392	-	0.82	0.1875
210	410	-	0.70	0.155
220	428	-	0.60	0.130
230	446	-	0.51	0.109
240	464	-	0.44	0.092
250	482		0.35	0.078
260	500		0.33	0.067

This details will help.

Thanks.

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