2PCS FLS821-012-1A Automotive Relay Replacement, Plug-in Power Relay, SPST-NO, 12V 40A, Replaces RTT7114/MB141967 / MB141968 / MB141969 / MB141980 / MB399789 / 804-1A-C1 for Fuse/Relay Box Circuits

FLS821-012-1A 12V High-Current Automotive RelayThis listing is for an OE-number/footprint matched replacement relay. Please confirm the OE number on your original relay and verify the socket/pin layout using your vehicle manual before purchase.Key Specifications (per FLS821 series spec)OE/Fit code: FLS821-012-1A (coil code 012 = 12VDC)Contact form: 1A / SPST-NO (normally open)Max operating current: 40A; max switching voltage: 27VDCRated resistive load: 40A @13.5VDC; 20A @27VDCQuick-connect terminals; contact material: AgSnO2Operating temperature: -40°C to +85°C; operate/release ≤10ms, release ≤5msInsulation resistance: 100MΩ; dielectric strength (coil-contact): 500VACWhat it does / When to replaceSwitches battery power to a high-current circuit when triggered by a low-current control signal (application depends on relay slot).Possible symptoms of a weak relay: intermittent loads, no output, clicking, load stuck ON/OFF, or heat at the relay socket.Fitment reminder: Do not buy by vehicle year/model alone. Confirm fitment by OE number FLS821-012-1A and by matching the relay footprint and pin layout in the fuse/relay box.

• SPEC & FEATURES: OE/Fit code FLS821-012-1A (FLS821 series); coil code 012 = 12VDC. Contact form 1A / SPST-NO high-current automotive relay; quick-connect terminals. Max operating current 40A; max switching voltage 27VDC; rated resistive load 40A @13.5VDC and 20A @27VDC (resistive). Contact material AgSnO2; insulation resistance 100MΩ; dielectric strength 500VAC (coil-contact). Operating temp -40°C to +85°C; operate/release time ≤10ms and release ≤5ms; mechanical life 1×10^6, electrical life 1×10^5 (per FLS821 spec).
• INSTALL & SAFETY: Disconnect the battery before service. Locate the correct relay slot using your vehicle manual/fuse box legend. Pull the relay straight up (do not pry on the terminals); inspect the socket for melting, looseness, or corrosion and repair the connector if needed. Before buying, match the printed OE number (FLS821-012-1A) AND the pin/terminal layout and height/footprint of your original relay. If your original relay uses coil suppression (resistor/diode), replace with the same type to avoid electrical noise or ECU/BCM issues. After installation, confirm the load operates normally and the relay/socket stays cool under normal use.
• FITMENT (NO GUESSING): Part-number based replacement—Confirm fitment by OE number FLS821-012-1A and by matching relay footprint/height plus pin markings on the original relay and fuse/relay box socket. Search terms covered: 12V 40A relay replacement, SPST normally open relay, high current fuse box relay, quick-connect plug-in relay. If you cannot verify the OE number on your old relay or in the manual, do not purchase by vehicle year/model alone.
• SYMPTOMS & USE (CIRCUIT DEPENDS ON SLOT): High-current relays switch power to vehicle loads that may include radiator/condenser fans, auxiliary lights/fog lamps, horn, blower motor feed, or A/C clutch control—your exact application depends on the labeled relay position. Common relay failure signs: intermittent operation, clicking with no output, no power to the load, load stuck ON/OFF, overheating smell, or heat-discolored terminals. For diagnosis, you may swap with another identical relay ONLY if the part number and pin layout match and the circuits are equivalent (per manual).
• BUYER CHECKLIST: Verify 12V coil, SPST-NO (1A) contact style, and 40A rating using the markings on your existing relay and the service manual. If your fuse box uses multiple identical relays, keeping a spare with the same OE number can speed troubleshooting; replace heat-damaged sockets/connectors to prevent repeat failures.