OBD-II trouble code
P0695: Fan 3 Control Circuit Low
The third fan control output has been pulled toward ground. Before hunting for a third fan, count relays instead of fans — on a great many vehicles this output does not drive a fan at all, it reconfigures the two that are already there.
Quick facts
- System
- Powertrain
- Category
- Cooling / Electrical
- Severity
- Medium severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $60 – $800
- DIY difficulty
- Intermediate DIY
What does P0695 mean?
The most valuable thing to know about this code is something the name actively hides. Plenty of vehicles that can set it have exactly two cooling fans, and looking under the bonnet for a third one is an hour spent proving a negative. What those vehicles have is three fan relays, and the third one does not switch a motor on and off. It changes how the two motors are wired to each other.
The arrangement is common and elegant. Wire two identical fan motors in series and each one sees roughly half the supply voltage, so both turn slowly, quietly and draw modest current — that is low-speed cooling, which is all a vehicle needs most of the time. Switch the circuit so the two motors sit in parallel instead and each one now sees full voltage, so both spin hard. The relay that performs that reconfiguration is a third relay driven by a third module output, and the module refers to it by number in exactly the same way it refers to the other two. So a code naming fan 3 can perfectly well mean the high-speed stage rather than a physical device.
That is why the wiring diagram matters more on this code than on any other in the family. There genuinely are vehicles with three fans, mostly larger ones carrying extra coolers for transmission fluid, engine oil, power steering or charge air, and on those the code means what it appears to mean. There are others where the third output feeds an auxiliary pusher fan mounted ahead of the condenser. Deciding which of these three situations applies is the first job, it takes minutes with the right diagram, and getting it wrong invalidates everything after it.
The low-side fault produces a symptom picture that is unusual for a fan code, because the failure can be the fans running rather than the fans stopping. If a control circuit for a reconfiguration relay is shorted to ground, the module's command becomes irrelevant — the relay sees the ground it needs whenever power is present and stays energised. The result is a vehicle that comes on at key-on with both fans at full speed and never quietens down, at any temperature, in any weather. Owners describe it as a roaring noise, a car that sounds like it is overheating when it is not, and often a battery that struggles after short trips because a large continuous electrical load has appeared. In winter it can also mean an engine that takes an unusually long time to reach operating temperature and a heater that never gets properly hot, because the cooling system is being asked to work flat out against an engine that has barely warmed up.
Where the fault leaves the fans inert instead, the loss is the high-speed stage only. The vehicle retains its low-speed cooling and copes with ordinary driving completely normally, so nothing at all is apparent until demand exceeds what half-voltage fans can carry: towing, a long climb, a hot day with the air conditioning at maximum, sitting in stationary traffic in summer. That is why this fault so often announces itself on the first trip with a trailer, and why a vehicle can carry it for months looking perfectly healthy.
Common causes
- Fan 3 relay control wire shorted to ground, leaving the relay energised regardless of what the module commands
- Fan 3 relay shorted internally or with contacts welded closed
- Chafed harness where the fan wiring crosses the radiator support, shroud or fan carrier
- Water and corrosion inside the underhood relay box drawing the control circuit down
- Third or auxiliary fan motor shorting internally on vehicles that genuinely have one
- Damage from previous cooling system, condenser or front-end work
- Corroded or bridged relay socket terminals
- Failed module output driver for the fan 3 circuit, which should be confirmed only after the wiring is cleared
Symptoms
- Both cooling fans running at full speed from key-on and never switching off, even on a cold engine
- Constant loud fan noise that owners often mistake for an overheating engine
- Engine slow to reach operating temperature and weak cabin heat in cold weather
- Battery drain or a charging system working unusually hard on short journeys
- Alternatively, cooling that is adequate in normal driving but fails under tow, on grades or in hot stationary traffic
- Coolant temperature climbing only under heavy load, then recovering once the load is removed
- Check engine light with no drivability change of any kind
- Blown fan-circuit fuse where the short to ground is a hard one
Diagnostic steps
- 1.Pull the wiring diagram for this exact vehicle and establish what the fan 3 output actually drives. On many vehicles it is a series-to-parallel reconfiguration relay rather than a third motor, and assuming a third fan exists is the single most common wasted hour on this code.
- 2.Count relays rather than fans. Three fan relays with two motors is a normal, deliberate design and it tells you immediately which kind of system you are working on.
- 3.Note whether the fans are running constantly or not running at all, because on a low-side fault both are possible and they lead in opposite directions. Constant running points at a control circuit held to ground; no high-speed operation points at the relay or its load side.
- 4.Unplug the fan 3 relay. If constantly running fans stop, the fault is on the control side of that relay rather than in the motors.
- 5.With the relay unplugged, check the control wire for continuity to ground when nothing is commanding it. A grounded reading at rest confirms the short.
- 6.Swap in a known-good identical relay to rule out welded contacts.
- 7.Test the high-speed stage deliberately rather than waiting for it. Command it with a scan tool if possible, or let the engine idle with the air conditioning on maximum until the upper fan threshold is reached, and confirm the step change in fan speed actually happens.
- 8.Inspect the relay box for water ingress, green terminals and evidence of previous flooding, since a shared corroded ground path inside the box can affect more than one circuit.
- 9.Compare against the fan 1 and fan 2 circuits. Faults on more than one fan output at once point to a shared feed, ground or the relay box itself rather than three separate failures.
Repair cost
$60 – $800
A fan relay is $15 to $80 in parts, so a relay-only repair lands around $90 to $170. Diagnosis tends to run at the higher end here, $110 to $190, because establishing what the third output actually controls is real work before any testing starts. A shorted control wire repair is $130 to $400 depending on access. On vehicles that genuinely have a third or auxiliary fan, replacing that motor or its assembly is $250 to $800. If the fault turns out to be a corroded or water-damaged underhood relay box, budget $300 to $700 for the housing and the labour to transfer everything into it.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with cooling fan relay replacement preselected. Adjust labor rate and vehicle category to fit your situation.
DIY vs shop
This is an intermediate DIY job. It usually involves diagnostic steps, specialty parts, and some careful work in tight spaces. If you have the tools and a service manual or trustworthy video for your specific vehicle, it is achievable in a weekend. Otherwise, a competent independent shop will be faster.