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Bmw 318I Auxiliary Engine Cooling Fan Relays

Bmw 318I Auxiliary engine cooling fan relays

Starting at $60.95, AutoBuffy stocks 1 auxiliary engine cooling fan relays from Four Seasons. This relay switches power to the electric radiator fan that runs when the A/C is on or coolant temperature climbs above threshold. When it fails, the fan stops running on demand, coolant temps spike, and engine damage follows quickly.

Signs your Bmw 318I needs a new auxiliary engine cooling fan relay

  • Engine temperature gauge climbs into the red during stop-and-go traffic or while idling
  • Auxiliary cooling fan never runs even when A/C is switched on or coolant is hot
  • Auxiliary fan runs continuously at full speed and won't shut off with the ignition
  • A/C blows warm air at idle because the condenser fan isn't pulling air across the coils
  • Coolant overflow reservoir repeatedly overflows or boils over during short drives
  • OBD-II scanner shows cooling fan circuit fault codes related to relay control or fan speed

Which auxiliary engine cooling fan relay should you buy for your Bmw 318I?

The main decision is whether to buy an OE-spec relay, a heavy-duty upgrade, or a complete relay-and-fuse-box kit. Fit and amperage rating matter most here — an undersized relay will burn out quickly under the sustained current draw of an electric fan motor. Always match the relay's pin configuration and coil voltage to the original.

OE-Replacement Relay
Best for
Restoring factory behavior on a stock cooling system
What you get
Exact pin count, coil resistance, and amperage rating to match the original; direct plug-in fit
Heavy-Duty Upgraded Relay
Best for
High-mileage vehicles or those driven in extreme heat
What you get
Higher continuous amperage rating and reinforced contacts that resist heat-induced arcing and pitting
Relay + Pigtail Connector Kit
Best for
Vehicles with corroded or melted relay sockets
What you get
New relay paired with a pre-terminated wiring pigtail to eliminate the damaged connector entirely
Fuse/Relay Box Assembly
Best for
Vehicles where heat damage has spread beyond the single relay
What you get
Full underhood fuse and relay center replacement that restores the entire circuit rather than just one component

Auxiliary engine cooling fan relays brands we stock for your Bmw 318I

Four Seasons
1 option · from $60.95

Replacing the auxiliary engine cooling fan relay on a Bmw 318I

Easy⏱ 15–30 minutesRelay puller or small flat-blade screwdriverDigital multimeterTest lightOwner's manual or fuse box diagram

Locate the correct relay cavity using the fuse box cover diagram, pull the old relay straight out, and press the new one firmly into the same socket until it seats. Before buttoning up, confirm the repair by starting the engine, switching on the A/C or letting coolant temperature rise, and verifying the auxiliary fan runs. No torque specs apply — this is a friction-fit connector swap.

Frequently asked questions

How much does it cost to replace auxiliary engine cooling fan relays on a Bmw 318I?
The relay itself starts at $60.95 at AutoBuffy. DIY total cost stays close to that part price since no special equipment is required. Shop labor for relay diagnosis and replacement is typically billed at under an hour, so total out-of-pocket at a repair facility remains modest compared to most cooling system repairs.
Can I drive my Bmw 318I with a failed auxiliary cooling fan relay?
Only for very short distances in cool conditions. Without the auxiliary fan running, your Bmw 318I has no active airflow across the radiator at idle or low speed. Coolant temperature can reach dangerous levels within minutes in traffic, risking head gasket damage, warped cylinder heads, or a full engine overheating event.
How do I know if the relay is the problem and not the fan motor itself on my Bmw 318I?
Bypass the relay by jumping power directly to the fan motor connector. If the fan spins normally with direct power, the motor is good and the relay or its control circuit is the fault. If the fan still doesn't run with direct power applied, the motor itself has failed and the relay is not the root cause.
Where is the auxiliary cooling fan relay located on a Bmw 318I?
On most Bmw 318I applications it sits in the underhood fuse and relay box, sometimes labeled 'COOLING FAN' or 'RAD FAN' on the cover diagram. Some platforms mount a dedicated cooling fan relay module near the radiator or on the fender well. Check the fuse box lid diagram or a wiring schematic for the exact cavity.
What causes auxiliary cooling fan relays to fail on a Bmw 318I?
Relay contacts burn and pit over time from the high current spikes each time the fan motor starts. Heat from the engine bay accelerates coil insulation breakdown. A failing fan motor that draws excessive amperage is the most common root cause — replace a seized or sluggish fan motor at the same time or the new relay will fail prematurely.
Will a bad auxiliary cooling fan relay affect A/C performance on my Bmw 318I?
Yes, directly. The auxiliary fan is responsible for pulling air through the A/C condenser when the vehicle is stationary or moving slowly. Without it, refrigerant head pressure rises, the A/C compressor cuts out on high-pressure protection, and cabin cooling drops off noticeably at idle — a symptom often misdiagnosed as a refrigerant or compressor issue.

Shop auxiliary engine cooling fan relays by year for the Bmw 318I

19991998199719961995199419931992199119851984

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