Recognizing Early Signs of Cylinder Head Temperature Sensor Failure in Porsche 911

You won’t find engines as excellent as those made by German automaker Porsche…

The efficiency at which a Porsche engine extracts energy from fuel is truly phenomenal. Today’s blog post is about a sensor that plays a crucial role in enabling this performance excellence. As you might have guessed by now… we are talking about the ‘cylinder head temperature sensor’.

Cylinder Head Temperature Sensor: What Makes It So Important?

Don’t be fooled by its trivial appearance… this small cylindrical, metal-made component enables the control module keep track of the engine temperature in real-time.

It is essentially a Negative Temperature Coefficient thermistor… With the increase in temperature, its resistance decreases. This change in resistance is then converted into an electrical signal and conveyed to the engine management computer to be processed.

The equations shared below might help you understand the behavior of an NTC thermistor used in Porsche 911 cylinder head temperature sensor or CHT.

T- Temperature in K

T0 - Referrence temperature

R- Thermistor resistance

R0 - Thermistor resistance at T0

B- Beta constant

Vin- Supplied voltage

Rfixed- Fixed resistor in the voltage divider circuit

Why It Might Cease Functioning

The CHT sensor your Porsche 911 comes equipped with is made of high-temperature resistant material… and is not supposed to fail very often.

However, the sensor becomes vulnerable to all sorts of issues as it ages. It may become corroded due to accumulation of moisture. Its communication with the ECM might get disrupted because of electrical issues. Its sensing element might get frayed due to continual exposure to extreme engine temperatures.

Whatever the reason may be… if your 911’s CHT sensor is defective, have it checked by a certified professional.

How to Know if It Has Stopped Working

Listed below are a few signs you can look for if you suspect a glitch in your vehicle’s CHT sensor…

#1- Fluctuating engine temperature readings

So, your Porsche’s engine temperature gauge readings have been fluctuating a lot during the past few days without any specific reason… It could be indicative of a glitch in the CHT sensor.

#2- Overheating/ underheating

Has your Porsche engine been struggling to reach the ideal operating temperature or running abnormally hot lately? If such is the case, there is a slight possibility that the CHT is no longer sending the control module the requisite data.

#3- Reduced engine efficiency

Since the engine management computer relies on real-time temperature readings from the CHT sensor to control different aspects of engine operations, such as adjusting the air-fuel mixture, regulating the ignition timing, etc… if the CHT sensor malfunctions, it will impact the way your Porsche engine operates.

#4- Rough idling/ stalling

Your Porsche engine will find it hard to maintain a steady RPM and may even stall at idle if its CHT sensor stops sending accurate temperature readings to the onboard computer.

Unavailability of temperature data might hinder the computer’s ability to maintain optimal air-to-fuel proportion inside the combustion chamber… resulting in poor combustion and erratic engine behavior.

#5- Longer cranking interval

Breathing life into your Porsche engine won’t be an easy task for you if the engine management computer fails to communicate with the CHT sensor.

An issue as trivial as a frayed wire in the circuit can cut off communication between the sensor and the computer… contributing to all sorts of drivability issues including extended cranking times.

#6- Engine warning light

Since it is the most obvious sign of any engine-related trouble, we decided to mention it in the last part of the article.

It is often accompanied by an error code… which can be retrieved from the fault memory using an OBD-II scanner. The code can then be used to pinpoint the exact nature of the issue you are dealing with.

Key Takeaways

1. The cylinder head temperature sensor or CHT helps the ECU keep track of the engine temperature more accurately.
2. Real-time temperature readings from this sensor help the computer regulate the air-to-fuel ratio inside the combustion chamber, determine ignition timing, among the other things.
3. It can malfunction due to corrosion, continual exposure to extreme engine heat, defective connectors, etc.
4. A faulty CHT sensor can impact the overall efficiency of your Porsche 911 engine.

So, if you’re noticing any of the above signs, have your vehicle’s CHT sensor checked at a nearby auto service center. Consider replacing the sensor if any deformity is found during the inspection.

We at Dart Auto are Denver’s finest German auto repair shop and have earned a reputation among drivers as consistently reliable and high performing vehicles in any condition. We specialize in servicing and repairing of most popular German vehicles.