The symptoms and causes of exhaust gas temp sensor failures

Used in over 30 per cent of all new vehicles, demand for aftermarket replacements has increased

The symptoms and causes of exhaust gas temp sensor failures
The location of Exhaust Gas Temperature sensors varies from vehicle to vehicle depending on the layout of the exhaust system.

The Exhaust Gas Temperature sensor is a thermistor element fixed in cement to protect from vibration and housed in stainless steel to withstand extreme temperatures of up to 900°C.

Changes in temperature result in changes in resistance of the sensor and this is communicated to the ECU as a voltage.

In a TechAssist bulletin, Lucas explain that these sensors protect vital exhaust components from overheating and help to control emissions.

They are also used in several combustion control processes in both diesel and petrol engines including selective catalytic reduction (SCR), turbo boost, exhaust gas recirculation and DPF regeneration.

A faulty sensor communicating incorrect voltages can result in poor fuel efficiency because the DPF regeneration takes longer to complete.

DPF regeneration

The DPF regeneration process can affect driveability.

Faulty exhaust gas temperature sensors can lead to unnecessary regenerations causing inconvenience for the driver.

Lucas say that some sensors are harder to diagnose than others.

PTC-type sensor failures are often misdiagnosed as DPF issues as after failure they continue to function sending incorrect signals to the ECU affecting the DPF regeneration process.

NTC-type sensors are more likely to trigger the engine check light on failure.

Extreme heat is often a cause of failure over time.

Lucas say a common problem with all wired sensors is that wires can break, especially if subjected to harsh twists and turns.

They are also easily damaged when replacing other components in the exhaust system.

As a result Lucas recommend that exhaust sensors are replaced at the same time as the exhaust system or components such as the DPF or CAT.

Exhaust Gas Temperature sensors have many features to help them withstand vibration but it can still take its toll over time.

Installation advice

1. Ensure the exhaust system is cool before starting work.

2. Handle the exhaust gas temperature sensor carefully, dropping the component may cause unseen damage to the cement that secures the thermistor.

3. If the sensor is threaded, clean the thread in the exhaust pipe with a cleaning tap.

4. Apply copper grease on the sensor thread only. Although some sensors are pre-greased, extra grease will prevent thread galling and reduce friction which could lead to over torque (especially with stainless steel thread.)

5. Tighten the sensor to the required torque as prescribed by the VM, using an open-ended torque wrench to avoid over-tightening and/or damage to the wire.

6. Turn the engine on and check if the exhaust system works properly. A reset of the ECU may be required.

From just 100 part numbers, Lucas Electrical’s exhaust gas temperature sensor range covers over ten million vehicles on the road.

To find out more about and to view Lucas Electrical’s range of exhaust gas temperature sensors, select ‘more details’ below.

Home Page Forums The symptoms and causes of exhaust gas temp sensor failures

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  • #156323 Reply

    The Exhaust Gas Temperature sensor is a thermistor element fixed in cement to protect from vibration and housed in stainless steel to withstand extrem
    [See the full post at: The symptoms and causes of exhaust gas temp sensor failures]

    #178626 Reply
    charlie pinches
    Guest

    Was hoping you could help,

    My exhaust gas temperature sensor was reading zero degrees, I’ve had this replaced and it’s still reading zero degrees. Does anyone have any ideas as to what it could be?

    #181803 Reply
    Kevin Gaudreau
    Guest

    have you gotten an answer yet

    #201989 Reply
    NEIL SCHMIERER
    Guest

    HI HAVE HYUNDAI SANTA FE 2007 TURBO DIESEL HAD TURBO CHANGED AND NOW VEHICLE STOPS 15 MINUTES AFTER STARTING LOOKED AT TURBO AND NOTICED FRONT TEMP SENSOR NOT REFITTED CAN THIS THE CAUSE OF STOPPING
    THANKS FOR ANY ANSWERS

    #201990 Reply
    Meat-Head
    Blocked

    Neal Shoemaker hianddry santa fe

    Ram it back in and repeat, be surprised if it is.

    Does it cut dead, or like my dreams fade and die?

    #203689 Reply
    NEIL SCHMIERER
    Guest

    JUST CUTS OUT AS IF TURNED KEY OFF

    #213234 Reply
    Mike
    Guest

    Hello! My exhaust gas temperature sensor indicated -40 Celsius degree, I,ve got it replaced with a genuine one and the same fault. What could it be, please…?

Viewing 7 posts - 1 through 7 (of 7 total)

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