P0694
Fan 2 Control Circuit HighP0694 is a generic OBD-II powertrain diagnostic trouble code: Fan 2 Control Circuit High. It is logged by the engine control unit when the glow monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.
What P0694 means
P0694 is an SAE generic powertrain code set when the Engine Control Module (ECM) or Powertrain Control Module (PCM) detects an abnormally high voltage on the control circuit for Cooling Fan 2. Most modern vehicles use pulse-width modulated (PWM) or relay-switched low-side driver circuits to operate electric cooling fans. When the ECM commands the fan off but measures a voltage near battery voltage on the control line — or the measured feedback voltage is persistently above the expected high threshold — it stores P0694 and illuminates the MIL.
Cooling Fan 2 typically refers to the secondary or condenser fan in a dual-fan assembly, though on some platforms it identifies a high-speed fan relay circuit. Because the fan cannot be properly controlled, the ECM may disable air-conditioning compressor engagement or enter a protective cooling strategy. Continued operation with a faulty fan circuit risks chronic engine overheating, especially in stop-and-go traffic or while the A/C is running, which can lead to head-gasket or catalytic converter damage if ignored.
Diagnosis should begin at the fan relay and its fuse, then move to the harness between the ECM and the relay control coil. A short to voltage on the control wire — whether through chafed insulation, a failed relay coil, or an internal ECM driver fault — is the most common root cause. Internal ECM failures are relatively rare but do occur, particularly on high-mileage vehicles exposed to heat soak.
Common causes
Most-frequently reported root causes when P0694 is logged.
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1
Cooling fan 2 relay stuck closed or coil shorted internally, pulling control line high
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2
Short to voltage in the wiring harness between ECM and relay control terminal
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3
Blown or missing fan circuit fuse causing erratic voltage reference on control wire
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4
Failed fan motor creating a back-EMF spike that the ECM reads as high circuit voltage
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5
Corroded or high-resistance connector at the relay base or fan module
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6
Open ground on relay or fan module assembly
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7
Internal ECM output driver failure
Symptoms drivers notice
How to diagnose P0694
A typical diagnostic flow when this code is present.
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1
Retrieve freeze-frame data and confirm P0694 is current; note engine temperature at time of set
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2
Inspect the cooling fan 2 relay fuse and relay socket for corrosion, melted contacts, or a stuck-closed relay; swap relay with a known-good unit
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3
With ignition on and fan commanded off, backprobe the ECM control wire at the relay: voltage near battery level confirms a short to power in the harness
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4
Inspect the entire harness run from the ECM to the relay for chafing against hot or sharp surfaces; repair any shorts found
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5
Measure fan motor resistance and verify it is within specification; a shorted motor winding can damage the driver circuit
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6
If harness and relay check out, perform a relative compression or ECM pinout test per OEM procedure before condemning the ECM
Vehicles where we've handled P0694
Platforms in our catalogue with confirmed P0694 coverage.
Related powertrain codes
Frequently asked questions
Can I drive with P0694 stored?
Short distances in cool weather are generally low-risk, but the code means Cooling Fan 2 cannot be reliably controlled. In hot weather or with the A/C running, lack of cooling fan operation can cause overheating, so the fault should be repaired promptly.
Will P0694 cause the A/C to stop working?
Possibly. Many ECMs disable or limit A/C compressor engagement when a cooling fan circuit fault is active, because the condenser depends on the fan for airflow. Repairing the fault typically restores normal A/C operation.
Does P0694 always mean the relay is bad?
No. While a stuck-closed relay is the most common cause, a wiring short to voltage, a seized fan motor, or — rarely — a failed ECM driver can all produce the same high-circuit-voltage signature. Always trace the circuit before replacing parts.
Is P0694 the same as P0693 or P0695?
No. P0693 is the Cooling Fan 2 relay control circuit fault (general), P0694 specifically indicates a high-voltage condition on that circuit, and P0695 would indicate a low-voltage or open-circuit condition. Each points to a different type of electrical fault.
Disabling P0694 in software
RaceTune can permanently disable P0694 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.
ECUs with a P0694 disable in our catalogue
Confirmed coverage from our recipe database — we support many more families. Upload your file and our identifier will match it automatically.
- Bosch EDC17C74 verified 1 software version
- Bosch EDC17CP44 verified 1 software version
Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.
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