P0694
Fan 2 Control Circuit High
Powertrain Engine Cooling Fan Control Circuit 🟡 Moderate — Fix within a week
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What This Actually Means
In plain language — no jargon

The ECU detected excessive voltage in the cooling fan 2 control circuit, similar to a light switch being stuck in the "on" position with too much power flowing through it. This prevents proper fan speed control and can damage the fan motor or control module.

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Symptoms You May Notice
3 known symptoms for this code
Engine overheating or running hot
Cooling fan runs continuously at full speed
Check Engine Light illuminated
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Embedded Systems Insight
What the ECU/ECM is actually computing

The ECU monitors voltage output to the Fan 2 control circuit, which should toggle between low (off) and ground (on) to vary fan speed. When voltage stays abnormally high instead of switching properly, the ECU logs a fault. The control module expects to see clean PWM (pulse-width modulation) signals or relay activation, not constant elevated voltage.

Voltage & Parameter Thresholds

Parameter Normal Range Fault Condition
Fan 2 Control Voltage 0V (off) to variable PWM signal Sustained voltage above expected threshold (typically >5V when should be 0V)
Control Circuit Resistance Low resistance when energized Open circuit or shorted to power supply
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Diagnostic & DIY Fix Guide
Check these in order — from cheapest to most complex
1
Cooling fan relay
Locate and swap the Fan 2 relay with an identical relay from another circuit to verify if fault moves.
2
Fan 2 control wiring and connectors
Inspect harness for pinched wires, corrosion, or loose connectors between ECU and fan motor; reseat all connections.
3
Cooling fan motor assembly
Test fan motor resistance with multimeter; replace if shorted or if wiring tests pass and relay swap didn't resolve issue.