Defective lambda sensor: Symptoms, causes & repair costs

Lambda sensor defective – What does that mean?

The lambda sensor is a crucial component in modern vehicles. It measures the oxygen content in the exhaust gas and ensures that the fuel-air mixture is optimally regulated. This reduces fuel consumption and minimizes emissions.

If the lambda sensor is defective, this can have serious consequences: higher fuel consumption, poor engine performance or problems with the TÜV. But how can you tell if the lambda sensor is no longer working properly? And what does the repair cost?

In this blog, you can find out all the important symptoms, causes and what costs you may incur.

Symptoms of a defective lambda sensor

A faulty lambda sensor often manifests itself in various ways:

1. Increased fuel consumption

As the lambda sensor no longer regulates the air/fuel mixture correctly, the engine may inject too much fuel. The result: Your car consumes more fuel than usual.

🔍 Good to know:

A defective lambda sensor can increase fuel consumption by up to 15 %!

2. Engine runs unevenly or jerks

An incorrect air/fuel mixture can lead to the engine no longer running smoothly or jerking – especially when accelerating or idling.

3. Loss of power & delayed throttle response

If the engine responds to the accelerator pedal with a delay or loses power, a faulty lambda sensor could be the cause.

4. Engine control light lights up

The engine control light comes on if the lambda sensor is providing incorrect values or has failed completely. In this case, you should have the error read out.

💡 Tip:

You can use an OBD scanner to find out for yourself whether the lambda sensor is affected. Typical error codes are P0130 to P0167.

5. Strong smell of gasoline from the exhaust

If the fuel-air mixture is not optimal, unburned fuel may enter the exhaust. This leads to a strong smell of gasoline.

6. Increased exhaust emissions & problems with TÜV

The lambda sensor ensures optimum exhaust gas regulation. If it is defective, emissions increase – which can lead to your car failing the emissions test.

Causes of a defective lambda sensor

A lambda sensor can be damaged by various factors. The most common causes are

• Age-related wear – A lambda sensor lasts for around 100,000 to 150,000 kilometers. After this, the risk of a defect increases.
• Contamination from oil residue or soot – Deposits can impair the measuring accuracy of the sensor.
• Defective wiring or corrosion – Loose cables or damaged plug connections can cause incorrect signals.
• Engine damage or incorrect fuel mixture – A poorly adjusted engine can overload the sensor.
• Water or coolant in the exhaust tract – A leaking cylinder head gasket can cause coolant to enter the exhaust system and damage the sensor.

How is a defective lambda sensor diagnosed?

If you notice one or more of the above symptoms, you should have a diagnosis carried out.

Options for diagnosis:

✔ Read out the fault memory – An OBD scanner displays fault codes that may indicate a defective lambda sensor.

✔ Voltage measurement – A workshop can check whether the sensor is still working correctly.

✔ Visual inspection – If the sensor is heavily sooted or mechanically damaged, it must be replaced.

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How much does it cost to replace a lambda sensor?

The cost of replacing a lambda sensor depends on the vehicle model and the workshop.

• New lambda sensor: €50 – €250
• Installation costs in the workshop: €50 – €150
• Total costs: 100 – 400 €

🔍 Good to know:

Many vehicles have two lambda sensors – one before and one after the catalytic converter. If one sensor is defective, the second should also be checked.

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Is the repair worthwhile or does it make sense to sell the car?

Replacing the lambda sensor is usually cheaper than major engine repairs. However, if your vehicle already has many kilometers on the clock and more and more defects are occurring, it may be worth selling it.

If your car is causing high repair costs or there are problems with the emissions test, you can consider selling it.

Sell easily & safely with CashforCars.de

If you no longer want to invest in expensive repairs, CashforCars.de is your point of contact. Whether your car has a lambda sensor defect, engine damage or other problems – we buy it reliably.

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Whether a repair is still worthwhile or selling is the better decision depends on the overall condition of your car. With us, you'll always get a quick and fair solution!

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Conclusion: Lambda sensor defective? Act now!

A defective lambda sensor can lead to higher fuel consumption, loss of power and problems with the emissions test. The cost of replacement is between 100 and 400 euros, depending on the vehicle model.

If the repair is no longer worthwhile or your car is increasingly causing problems anyway, selling it may be a sensible alternative. With CashforCars.de, you can sell your car quickly and easily – regardless of its condition!

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