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Knock Sensor Replacement
Typical Cost: Low
Mobile Repair? Yes
Typical Lead Time: 24 - 48 hours depending on part availability
What does a knock sensor do?
The knock sensor is used to detect vibrations and detonation “knock” from an engine and send a signal to the engine control unit to prevent engine damage.
How does a knock sensor work and what are the components?
The knock sensor is bolted directly to the engine itself. When vibrations occur, the sensor converts these into an electrical signal which the engine control unit evaluates. If this interpretation is outside of the pre defined limits, the engine management control unit will alter the ignition timing until it returns to within tolerance.
Typical symptoms that require a knock sensor to be replaced.
Typically a failed knock sensor will result in one or some of the following symptoms;
- Engine pre-detonation known as “pinking” or knocking
- Higher fuel consumption
- Poor running and performance
- Illuminated engine management light (EML)
What happens during a knock sensor replacement?
Changing knock sensors is a routine repair for all mechanics and can be done both kerbside as well as in the workshop, providing it is safe to do so.
Whilst there are variations between manufacturers, the basics are pretty similar.
The mechanic will;
- Assess the situation by reading the diagnostic codes and checking live data
- Once confirmed that the knock sensor is faulty, continue on to replacing it.
- Once replaced, start the engine and recheck the error codes
What does this repair cover?
Unless otherwise stated, the quote for your knock sensor to be replaced will cover;
- The cost of the knock sensor
- Coming to you
- Fitting of the parts
- Disposal of the old parts (unless you request to keep them)
- VAT (if applicable)
- 12 months parts and labour warranty
What to search for on the ClickMechanic site?
Knock sensor replacement
How much does it cost to have a knock sensor replaced?
The cost of a knock sensor replacement depends on your car and what parts your car's manufacturer recommends.
Find out what you could save by visiting ClickMechanic
https://www.clickmechanic.com/bookings/car
FAQ’s
Can I supply my own parts?
No, we will not fit customer supplied parts unless they are a brand new item, purchased from a dealership with the receipt as proof of purchase. There is no flexibility over this due to insurance and warranty issues.
What happens if the mechanic finds that the knock sensor doesn’t require changing and the problem is due to another issue?
In this scenario, the mechanic will provide a no obligation quote for the correct repair. Should you accept this, the mechanic can alter the booking accordingly. If you decide not to go ahead with the alternative repair, the mechanic can change the booking to a call out and diagnostic booking and charge according to the time spent with the vehicle and call out.