P0693 – Fan 2 Control Circuit Low

DTC P0693 is an ISO/SAE controlled powertrain code that sets when the PCM/ECM detects the Fan 2 Control Circuit Low condition. In other words, the vehicle’s controller commanded the second cooling fan control circuit to a specific state, but the electrical voltage on that control circuit stayed lower than expected. This is a circuit low fault type, so the focus is on electrical integrity—wiring, connectors, relay/module control, and the driver circuit—rather than assuming the fan motor itself has failed. Because cooling fan control affects engine temperature management and can influence A/C operation and heat load, addressing P0693 promptly helps prevent overheating and secondary drivability issues.

P0693 Quick Answer

P0693 – Fan 2 Control Circuit Low means the PCM/ECM saw the Fan 2 control circuit voltage lower than expected when it tried to control Fan 2. Prioritize checks for a short-to-ground, damaged wiring near the fan/radiator area, poor connector pin fit or corrosion, and faults in the Fan 2 relay or fan control module circuitry before replacing the fan motor.

What Does P0693 Mean?

P0693 officially means: Fan 2 Control Circuit Low. The PCM/ECM monitors the electrical behavior of the circuit used to control “Fan 2” and compares the observed voltage to what it expects when the circuit is commanded on or off. If the circuit voltage is pulled down (or remains too low) outside the expected range, it interprets that as a circuit low condition and stores P0693.

This code describes an electrical problem on the Fan 2 control circuit, not a guaranteed mechanical failure of the fan motor. A circuit low condition is typically consistent with a short to ground, an internally shorted component that drags the circuit down, or a control-side fault that prevents the circuit from achieving the expected voltage level when commanded.

Theory of Operation

Most vehicles with multiple cooling fan strategies use a dedicated control circuit for a second fan or a second fan stage. The PCM/ECM determines when additional airflow is needed using inputs such as engine coolant temperature, A/C request, A/C pressure, vehicle speed, and sometimes transmission or intake air temperature. Based on these inputs, the PCM/ECM commands Fan 2 operation through a control path that may involve a relay, a fan control module, or a solid-state driver.

In a typical relay-based design, the PCM/ECM may control the relay coil by switching the control circuit to ground or supplying a control voltage (design-dependent). In a module-based design, the PCM/ECM sends a control signal to a fan control module, which then powers the fan. P0693 sets when the PCM/ECM detects the Fan 2 control circuit voltage is low compared to the expected value for the commanded state, indicating the circuit is being pulled down or cannot rise to the correct level.

Symptoms

• Malfunction Indicator Lamp (MIL) illuminated
• Cooling fan performance concerns involving Fan 2 (may not run when commanded)
• Engine temperature may rise higher than normal in low-speed conditions if Fan 2 is unavailable
• A/C performance may degrade at idle or low speed due to reduced airflow across the condenser
• Cooling fan operation may be intermittent if the low-voltage condition is intermittent (for example, connector or harness movement related)
• Additional cooling-fan-related DTCs may be present depending on vehicle strategy

Common Causes

• Fan 2 control circuit short to ground
• Damaged wiring insulation or pinched harness in the Fan 2 control circuit
• Corroded, loose, or spread terminals in Fan 2 related connectors (relay/module/fan harness)
• Faulty cooling fan relay (if equipped) that loads or pulls the control circuit low
• Faulty fan control module (if equipped) affecting the control circuit voltage
• Poor ground or power distribution issue that causes abnormal control-circuit voltage behavior under load
• PCM/ECM driver or internal control circuit fault (should only be considered after external circuit verification)

Diagnosis Steps

Tools needed: bi-directional scan tool (able to command Fan 2), digital multimeter (DMM), wiring diagram for the specific vehicle, back-probing pins, and a test light or fused jumper as appropriate. A current clamp can be helpful for confirming electrical loading when the fan is commanded.

1. Confirm the DTC and capture data: Verify P0693 is present (stored/pending). Record freeze-frame data and note battery voltage, coolant temperature, and A/C request at the time of the fault.
2. Check for related codes: Look for additional cooling fan, temperature sensor, A/C pressure, or power/ground related DTCs that could affect fan commands or circuit behavior. Diagnose power/ground or communication issues first if present.
3. Perform a visual inspection: Inspect the Fan 2 control circuit wiring harness routing near the radiator support, fan shroud, fuse/relay area, and any inline connectors. Look for chafing, pinch points, melted insulation, or evidence of contact with sharp edges.
4. Inspect fuses and power distribution: Check all fan-related fuses, fusible links, and the fuse/relay box for heat damage, looseness, or corrosion. Confirm proper battery voltage supply where required by the fan system.
5. Use the scan tool to command Fan 2: With key on (and conditions met per scan tool capability), command Fan 2 on and off. Observe whether Fan 2 responds and whether the DTC resets immediately or only after specific conditions.
6. Check the Fan 2 control circuit for a short to ground: With the appropriate connectors disconnected (per wiring diagram), measure resistance from the Fan 2 control wire to chassis ground. A low resistance reading indicates the control circuit may be shorted to ground; isolate by separating harness sections and re-testing.
7. Verify control-circuit voltage behavior: Back-probe the Fan 2 control circuit at the relay/module connector. Command Fan 2 on/off and verify the control voltage changes as expected for that design. If the circuit stays low regardless of command, continue isolating whether the low condition is due to wiring, a loaded component, or the control driver.
8. Check connector integrity under real conditions: Inspect terminals for corrosion, looseness, or spread. Perform a light tug test on each wire at the connector. If safe and appropriate, gently wiggle the harness while monitoring the control signal to identify intermittent drops.
9. Evaluate the relay or fan control module (as equipped): If the vehicle uses a relay, test relay coil resistance and inspect the relay socket for heat damage. If it uses a fan control module, confirm the module has correct power and ground and that the control input is not being pulled low due to an internal fault.
10. Confirm repair and run verification: After repairs, clear codes and command Fan 2 multiple times. Road test through conditions that would normally request Fan 2 operation. Recheck for pending/stored P0693 and confirm consistent fan control circuit behavior.

Professional tip: Because P0693 is a circuit low code, prioritize finding what is pulling the control circuit down. A quick continuity check can miss faults that only appear when connectors are loaded or when vibration/heat changes resistance. Verify the control circuit voltage while commanding Fan 2 and isolate the low condition by disconnecting components one at a time (following the wiring diagram) to see when the control voltage returns to normal.

Possible Fixes

• Repair or replace damaged wiring in the Fan 2 control circuit (especially any short-to-ground points)
• Clean, repair, or replace corroded/loose terminals or connectors related to Fan 2 control
• Replace the cooling fan relay (if equipped) after confirming it is loading the control circuit or malfunctioning
• Repair power/ground distribution issues affecting the fan control system (fuse/relay box terminals, grounds, power feeds)
• Replace the fan control module (if equipped) after verifying correct power/ground and confirming the module pulls the control circuit low
• Consider PCM/ECM repair or replacement only after proving external wiring and components are correct and the driver output remains improperly low

Can I Still Drive With P0693?

Driving with P0693 is not recommended for extended periods because a Fan 2 control circuit low condition can prevent the vehicle from providing the intended cooling airflow under higher heat-load situations. If Fan 2 does not operate when required, engine temperature can rise in traffic, during long idling, or when A/C load is high. If you must move the vehicle, monitor engine temperature closely and avoid conditions that increase heat load. If the temperature rises above normal, stop driving to prevent overheating-related engine damage.

How Serious Is This Code?

P0693 can be serious because cooling fan control is a key part of thermal management. The severity depends on whether Fan 2 is required to maintain safe coolant temperatures under the current operating conditions. Even if the engine seems normal at cruising speeds, low-speed operation, idle, and high ambient temperatures can expose the problem quickly. Since this is a circuit low fault, correcting the underlying electrical issue is important to restore reliable fan control and reduce the risk of overheating and heat-soak related performance concerns.

Common Misdiagnoses

A frequent misdiagnosis is replacing the cooling fan motor without proving the Fan 2 control circuit is functioning correctly. P0693 specifically indicates the controller observed the control circuit voltage as too low; that points first to wiring faults, connector issues, a relay/module that pulls the circuit down, or a driver problem. Another misstep is checking voltage only with connectors unplugged and concluding the circuit is good; a circuit can appear fine with no load yet drop low when connected due to corrosion, damaged terminals, or a component that drags the control line down.

Most Likely Fix

The most likely fix for P0693 is correcting an electrical fault that is pulling the Fan 2 control circuit voltage low—most often damaged wiring or poor connector/terminal integrity at the fan, relay/module, or nearby harness routing points. The correct approach is to verify the control signal with a scan tool command, then isolate the low condition by inspecting and testing the control circuit and related connectors until the circuit voltage behaves normally.

Repair Costs

Repair cost depends on whether the confirmed root cause is a sensor, wiring, connector issue, or control module problem. Verify the fault electrically before replacing parts.

Last updated: April 1, 2026