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Discussion Starter · #1 ·
Automotive parking light Car Vehicle Vehicle registration plate Grille

Wheel Tire Car Land vehicle Vehicle
Automotive parking light Car Vehicle Vehicle registration plate Grille
Wheel Tire Car Land vehicle Vehicle


Hey can anyone tell me what is wrong with my car I replaced the cylinder head temperature sensor. But the the wires on the harness are exposed and the codes are still showing. Now I hear a noise like air escaping when I accelerate. Also my heater hose is leaking. Could that be the problem. I took it to pep boys and they told me it might be a cracked cylinder head but I don’t believe them cuz they tried to sell me brake calipers and my calipers are fine.
 

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Since you're not explaining exactly what is wrong with your car, nor indicate what errorcodes are thrown, any comment on a possible fix is a shot in the dark.

Based on what you're saying between the lines it sounds like an overheating problem, and yes, a leaking heaterhose might contribute to that. Going with the cracked cylinder head diagnosis: 5 Symptoms of a Cracked Cylinder Head (and Repair Cost in 2021) - which may give you some means to diagnose and verify.

Start off with a detailed explanation of what is wrong with the car, possibly with feedback on the above diagnosis and what errorcodes are being thrown. That may help someone determine what might be a possible cause.
 

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Discussion Starter · #3 ·
Since you're not explaining exactly what is wrong with your car, nor indicate what errorcodes are thrown, any comment on a possible fix is a shot in the dark.

Based on what you're saying between the lines it sounds like an overheating problem, and yes, a leaking heaterhose might contribute to that. Going with the cracked cylinder head diagnosis: 5 Symptoms of a Cracked Cylinder Head (and Repair Cost in 2021) - which may give you some means to diagnose and verify.

Start off with a detailed explanation of what is wrong with the car, possibly with feedback on the above diagnosis and what errorcodes are being thrown. That may help someone determine what might be a possible cause.
It has a p1285 and a p1290 code. Sorry I thought I mentioned that
 

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P1285 Code - Cylinder Head Over Temperature Condition - P1285 Code - Cylinder Head Over Temperature Condition

Possible causes:

Engine overheated
Low engine coolant level
Faulty Cylinder Head Temperature (CHT) Sensor
Cylinder Head Temperature Sensor harness is open or shorted
Cylinder Head Temperature Sensor circuit poor electrical connection

P1290 Code - Cylinder Head Temperature Sensor Low Input - P1290 Code - Cylinder Head Temperature Sensor Low Input

Possible causes:

Wrong thermostat
Engine overheated
Low engine coolant level
Faulty Cylinder Head Temperature (CHT) sensor
Cylinder Head Temperature (CHT) sensor harness is open or shorted
Cylinder Head Temperature (CHT) sensor circuit poor electrical connection

Basically the 1285 codes are the same as the 1290 codes, with the exception of the thermostat. And these don't readily indicate a cracked cylinder head as a root cause. That's not to say it might still be cracked, but it's not one of the primary culprits. The engine overheating might (I think) have resulted in a cracked head, but since you aren't reporting the engine actually overheated, I'm discarding that as a cause.

Having a wrong thermostat means the engine either remains too cold or gets too hot before the coolant is being circulated. The needle on the dash indicating coolant temperature should be nice in the middle normally when the car is at operating temperature. If it is on the side of cold or warm that may indicate that the thermostat is the wrong model.

You replaced the CHT sensor. Unsure about the coolant level, you don't mention it being sufficient or too high/low. So might want to check that. The other two issues come back to electrical. Which you indicated with the 'exposed wires'.

Personally I'd insulate those with some isolation tape to make sure a short can't be the cause.

Also, may want to see if you have a good connection on the connector to the wires (seeing an 'open' situation may also occur). Basically unplug the sensor, and measure between the connector feet that the CHT sensor touches and the wires to see if they short inside the connector plug, or there's a break in the connector causing the 'open' fault. In which case it might just need a connector replacement.

Beyond that, see about using some contact cleaner on the connector to make sure there isn't dirt causing the issue. The other end of the cable ends up with the cars computer. I don't think that's directly the cause because then I'd expect a lot more issues, tho it's not in the realm of the impossible.

The above links to the enginecode pages also contain some additional information which might help you figure out what exactly is going on (I spotted a little movie on the 1285 code for Ford for instance).

The 'air escaping' sound doesn't sound related to this, and might be an aftermarket airfilter. I know mine was a bit more audible when switching to the aftermarket one.

Maybe someone else may have further ideas on this.
 

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If it is the connector, just remember:

The sensor should have a certain resistance (for instance 5 ohm - unsure what that sensor should normally provide resistance wise, tho I do suppose the amount of resistance changes with temperature, allowing the car to use the changing resistance as a measurement of temperature).

If the circuit is 'open', that means the resistance is infinite. There's a break in the loop coming from the car, going through the sensor, and returning to the car.
If the circuit is 'closed', that means the resistance is 0 ohm. Basically that means there's a short somewhere.

In both cases of infinite and 0 the car determines it can't talk to the sensor, and thus not get a reading, tossing the code.

Using a multimeter to measure the connections (with the car shut down, the circuit doesn't need to be powered for this type of measurement) should indicate if it's the connector or cabling that's at fault.
 

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Discussion Starter · #7 ·
I went ahead and bought a new connector and I’m going to wire it into the old wire a couple inches away from where it was open. I’ll let you know how it goes
 

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Which again comes back to P1289 Ford Code - Cylinder Head Temperature Sensor Signal Greater Than Self-Test Range

Possible causes:
Wrong thermostat
Engine overheated
Low engine coolant level
Faulty Cylinder Head Temperature (CHT) sensor
Cylinder Head Temperature (CHT) sensor harness is open or shorted
Cylinder Head Temperature (CHT) sensor circuit poor electrical connection


Atleast now it seems to detect a temperature, but the temperature found is out-of-scope for the vehicle. So the sensor seems to provide the wrong resistance based on temperature.

The Engine Control Module (ECM) detected the cylinder head temp above or below expected values

Beyond checking the wiring harness and connector (which you should already have done), are you sure the replacement CHT sensor you got is the same make/model as the one that came out, or atleast is one suited to the car? I'm unsure if someone fiddled with the ECM programming (tuning) that might have resulted in some change done that set the measurement values for the CHT sensor out of scope (can't imagine why one would want to change those parameters, but just thought I'd put it out there.

This might also help you verify the workings of the CHT sensor: StackPath

Said document also mentions the ground is shared with the O2 sensors, so not sure if you did anything to those. But those might also be worth checking if the wiring is still solid just in case.
 
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