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Lexus Is350 Heated Seat Relays

Lexus Is350 Heated seat relays

Starting at $200.95, AutoBuffy stocks 1 heated seat relays from Standard Ignition to fit the Lexus Is350. The heated seat relay is a small electromechanical switch that controls power delivery to the seat heating element. When it fails, your heated seats stop working entirely or cycle on and off erratically — a real problem in cold weather.

Signs your Lexus Is350 heated seat relay is failing

  • Heated seat produces no warmth at all, even after the button is pressed and the indicator light is on
  • Seat heater works intermittently — cuts out after a few minutes or only works on certain drives
  • Heated seat indicator light illuminates but the seat surface stays cold to the touch
  • Only one heat setting works (e.g., high works but low does not, or vice versa) due to a relay stuck in one position
  • You hear a faint clicking noise from behind the dash or under the seat when toggling the heat switch, but no heat follows
  • Blown fuse in the heated seat circuit that returns after replacement, indicating the relay is drawing excessive current

Which heated seat relay should you buy for your Lexus Is350?

The most important decision is matching the relay's amperage rating and connector type exactly to the original — an undersized relay will fail quickly, and a mismatched plug requires splicing that can introduce future faults. Beyond fitment, you can choose between OE-equivalent parts and upgraded heavy-duty relays depending on your budget and how long you plan to keep the vehicle.

OE-Equivalent Relay
Best for
Owners who want a like-for-like repair with guaranteed fitment
What you get
Matches original amperage rating, connector, and mounting tab; direct plug-and-play replacement
Heavy-Duty Relay (higher amp rating)
Best for
High-mileage vehicles or those with upgraded aftermarket seat heaters drawing more current
What you get
Stronger contact points, better heat dissipation, longer service life under continuous load
Driver-Side Relay
Best for
Replacing only the failed side to save cost when the passenger seat is confirmed working
What you get
Single relay sized and coded for the driver seat circuit; sold individually
Passenger-Side Relay
Best for
Targeting the passenger seat circuit specifically when diagnostics confirm that side is the fault
What you get
Single relay for the passenger seat circuit; often a different part number than the driver side on the same vehicle

Heated seat relays brands we stock for your Lexus Is350

Standard Ignition
1 option · from $200.95

Replacing a heated seat relay on a Lexus Is350

Easy⏱ 15–45 minutesOwner's manual or fuse box diagram (to identify correct relay slot)Relay puller or needle-nose pliersMultimeter (for circuit verification before and after)Trim removal tool (if relay is behind a panel)Flashlight or work light

Locate the relay in the fuse and relay box using the vehicle's fuse diagram, then use a relay puller or needle-nose pliers to remove it straight out without twisting. Press the new relay firmly into the same slot until it seats fully, then test the heated seat function before reinstalling any trim panels. No special torque or calibration is required — if the relay is correctly identified and fully seated, the repair is complete.

Frequently asked questions

How much does it cost to replace heated seat relays on a Lexus Is350?
The relay itself starts at $200.95 at AutoBuffy. DIY total cost is typically just the part plus minimal supplies. A shop will add one to two hours of labor, so expect a higher total if you have it professionally installed. Replacing the relay yourself is straightforward and keeps costs low.
How do I know if it's the relay and not the heating element or switch on my Lexus Is350?
Test the relay first by swapping it with an identical relay from another circuit in the fuse box, or use a multimeter to check for voltage on the output side when the seat switch is on. If voltage is present but the seat is cold, the element is likely the fault. No output voltage points to the relay or switch.
Where is the heated seat relay located on a Lexus Is350?
On most vehicles the heated seat relay sits in the interior fuse and relay box, often located under the dashboard, beneath a rear seat panel, or inside the center console. Check your owner's manual fuse diagram for the exact position. The relay is usually labeled 'HTD SEAT,' 'SEAT HTR,' or similar.
Can a bad heated seat relay drain my Lexus Is350's battery?
Yes. A relay stuck in the closed position will keep the heating element energized even with the ignition off, drawing continuous current and draining the battery overnight. If you notice a dead battery combined with a seat heater that won't fully shut off, a shorted relay is a likely cause worth checking immediately.
Is it safe to drive my Lexus Is350 with a failed heated seat relay?
A relay that simply causes the seat heater to stop working is not a safety hazard — you lose comfort, not vehicle function. However, a relay stuck closed and continuously powering the element can overheat seat components over time. In that case, pull the heated seat fuse as a precaution until the relay is replaced.
Do I need to replace both heated seat relays at the same time on my Lexus Is350?
Only the failed relay needs replacing. However, if both relays are original and the vehicle has high mileage, replacing the pair while you have the panel open is reasonable preventive maintenance. Relays on the same vehicle typically share the same age and duty cycle, so the second one may not be far behind.

Shop heated seat relays by year for the Lexus Is350

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Heated seat relays for other Lexus models

Lexus IS250Lexus HS250hLexus RX450hLexus ES350Lexus RX350Lexus IS F