A Guide to the Knock Sensor for the 2018-2019 Lexus LC500h
Understanding knock sensor issues in your LC500h is key to maintaining its unique hybrid performance.
- A failed knock sensor will trigger a Check Engine Light with codes like P0325 and cause poor performance.
- Labor costs are very high ($671-$985) because the sensors are under the intake manifold.
- Using a cheaper aftermarket sensor is risky; if it fails, you will have to pay the high labor cost again. Most experts recommend OEM parts.
- Before replacement, inspect the wiring harness for rodent damage, a common cause of knock sensor codes on Lexus vehicles.
Is Your Lexus LC500h Knock Sensor Failing?
A faulty knock sensor can cause noticeable problems with your vehicle's performance. Since this sensor is a key part of the engine management system, its failure can lead to poor engine performance and potentially trigger the vehicle to enter a protective "limp mode." While there are no widespread, common failures reported for this specific part on the LC500h, individual sensor or wiring issues can still occur.
Check for Rodent Damage
A very common cause for knock sensor error codes on Lexus vehicles is not the sensor itself, but the wiring leading to it. Rodents are often attracted to the soy-based wiring insulation and can chew through the wires, causing a bad connection. This is especially common for vehicles that are parked outside. Before committing to a costly repair, a visual inspection of the wiring harness for damage is a crucial first step.
Choosing a New Aftermarket Knock Sensor
When it comes to sensitive electronic components on a high-performance vehicle like the LC500h, the choice between Original Equipment (OEM) and aftermarket parts is critical. The labor to access and replace the knock sensors is very expensive, as it often requires removing the intake manifold.
- OEM/OEM-Equivalent: For Lexus vehicles, owners and experienced mechanics strongly recommend using OEM sensors or parts from the original manufacturer, like Denso. These parts are designed to meet the exact specifications for frequency response and durability that the Lexus ECU expects. Using an OEM part minimizes the risk of the part failing prematurely or not working correctly, which would force you to pay for the expensive labor all over again.
- Aftermarket Brands (Replacement, etc.): While a new aftermarket knock sensor is significantly cheaper, it comes with a risk. Aftermarket electronic sensors have a reputation for being less reliable on Toyota and Lexus vehicles. They may not solve the check engine light code or could fail within a short period. Given that the labor cost is the largest part of this repair, saving a small amount on a budget part is generally not recommended.
A Note on TSB L-SB-0006-21: You may find a Technical Service Bulletin (TSB) mentioning a "knock noise" for your vehicle. Be aware that this specific TSB refers to a noise from the brake actuator system when pressing the brake pedal, and it is completely unrelated to the engine's knock sensors.
Cost to Replace a Lexus LC500h Knock Sensor
The cost for this repair is dominated by labor due to the sensor's location deep in the engine valley.
| Part/Service | Estimated Cost |
|---|---|
| New OEM Knock Sensor (1) | $118 - $195 |
| New Aftermarket Knock Sensor (1) | $31.96 |
| Shop Labor | $671 - $985 |
| Total Replacement (Aftermarket) | $703 - $1017 |
| Total Replacement (OEM) | $789 - $1180 |
Note: Your LC500h has two knock sensors. While you may only have a code for one, many mechanics recommend replacing both at the same time, along with the wiring harness, since the labor to access them is the same. Prices are estimates and do not include taxes, fees, or potential additional repairs.
Frequently Asked Questions
Can I drive my LC500h with a bad knock sensor?
It is not recommended. While the car may run, you will experience reduced power and poor fuel economy. If the ECU detects a severe issue, it may put the car into a low-power "limp mode" to protect the engine, which can be unsafe in traffic. It's best to have the issue diagnosed and repaired promptly.
Where are the knock sensors located on the 2018-2019 LC500h?
On the Lexus 3.5L V6 engine, the two knock sensors are typically located under the intake manifold, in the valley between the cylinder heads. This location makes them difficult to access, which is why the labor cost for replacement is high.
Are there any recalls for the knock sensor on the LC500h?
No. As of early 2026, there are no specific safety recalls or technical service bulletins (TSBs) issued by Lexus or the NHTSA for engine knock sensor failure on the 2018-2019 LC500h.
Why is an aftermarket knock sensor so much cheaper?
Aftermarket parts are often cheaper due to different materials, manufacturing processes, and less extensive testing compared to OEM parts. For a sensitive electronic part like a knock sensor, these differences can lead to incorrect readings or a shorter lifespan, which is a significant gamble on a vehicle like the LC500h.
Technical Specifications
The 2018-2019 Lexus LC500h uses two knock sensors, one for each bank of its V6 engine.
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Lexus LC500h: