OBD-II Diagnostic Trouble Code
P0692 — Fan 1 Control Circuit High
P0692 indicates the fan 1 control circuit voltage is higher than expected. The ECM saw voltage on the fan driver circuit that suggests a short to battery voltage or, on many controllers, an open solenoid or relay coil.
Severity 3/5
Truck-relevant
Service this week
Severity
Service this week
Fan 1 Control Circuit High
Code
P0692
Category
Powertrain
Subsystem
Cooling
Truck-relevant
Yes
What this means for truckers
P0692 (Fan 1 Control Circuit High) — fan control output shorted to power.
Before you replace parts — try this first
P0692 on the Cooling system is most often open fan solenoid or relay coil — not a dead part. On commercial diesels especially, work these in order before spending money on parts:
- Confirm the symptoms. Match what your truck is doing to the Symptoms section below. If the code is set but the symptoms are not there, clear the code and re-test after a drive cycle — it may not return.
- Clean and dry the sensor connector. Water, road salt, or oil seeping into a connector is the #1 fake sensor failure. Disconnect, look for green corrosion or moisture, spray with electrical contact cleaner, dry, reseat. Many faults clear here for $0.
- Inspect the wiring harness. Trace the wire from the sensor toward the ECM — look for chafing against the engine block, melted insulation near the turbo or exhaust, or pinch points where a clamp has rubbed through.
- Test the sensor before swapping it. Most Common Causes (below) list the expected voltage or resistance range — a $20 multimeter saves a $300 sensor swap that does not fix the problem.
- Only then, replace the part. Use the OEM or a tier-1 aftermarket. Cheap sensors throw the same code in two weeks.
Symptoms
Fan may run continuously or never engage depending on whether the fan drive is normally engaged or disengaged, leading to either excess fan noise and fuel use or high coolant temperature and possible derate. Check-engine light is on.
Common causes
- CommonOpen fan solenoid or relay coil ($150–$700)
- CommonBroken wire or unplugged connector at the fan clutch solenoid ($80–$400)
- OccasionalFan control wire shorted to battery voltage ($150–$500)
- RareECM fan driver fault ($1200–$3500)
How to fix
Verify the fan connector is seated and terminals are intact
When to use: First, especially after radiator or front-end work
Check coil resistance of the fan solenoid or relay; replace if open
When to use: When connector is good
Check circuit for continuity to the ECM and for a short to power with components disconnected
When to use: When the coil tests good
Command the fan with a scan tool to verify operation after repair
When to use: After any repair
Affects most
No specific vehicle pattern found in our complaint database. This code can appear on any vehicle that supports OBD-II diagnostics.
Related
- → Browse all DTC trouble codes
- → Decode a VIN to check codes for your truck
- → Owner-operator maintenance guides
- → P0670 — Glow Plug Control Module Circuit
- → P0671 — Cylinder 1 Glow Plug Circuit
- → P0672 — Cylinder 2 Glow Plug Circuit
- → P0673 — Cylinder 3 Glow Plug Circuit
- → P0674 — Cylinder 4 Glow Plug Circuit
Frequently Asked Questions
Can I drive with code P0692?
P0692 is severity 3 — plan service within a few days. Performance is likely degraded already (you may feel reduced power, harsher shifts, or slightly worse fuel economy). Continuing to drive risks additional damage to adjacent components.
How much does it cost to fix P0692 on a commercial truck?
Total repair cost ranges $80–$3500 depending on the root cause. The cheapest fix is usually the first one listed below — Open fan solenoid or relay coil — which is also the most common. On commercial trucks the cost is usually higher than passenger vehicles due to part availability and shop labor rates ($120–185/hour at most truck shops, vs $90–130 at general auto shops). DIY-capable fixes (sensors, hoses, filters) are at the low end; major component replacements (turbo actuator, high-pressure fuel pump, transmission solenoid pack) are at the high end. Always diagnose with a scan tool BEFORE replacing parts — guessing wrong on a $1,500 turbo actuator when the actual issue was a $30 boost hose is a common expensive mistake.
Will P0692 fail a DOT inspection?
P0692 is generally not a direct DOT inspection fail item by itself. Inspectors focus on safety-critical systems (brakes, steering, tires, lights, hours-of-service). However, the check engine light alone can trigger additional inspection scrutiny. Best practice: fix the code and clear it before a planned inspection.
What's the difference between P0692 and related codes?
P0692 is closely related to: P0670 (Glow Plug Control Module Circuit), P0671 (Cylinder 1 Glow Plug Circuit), P0672 (Cylinder 2 Glow Plug Circuit), P0673 (Cylinder 3 Glow Plug Circuit). These codes share the same subsystem (cooling) and often appear together. If you see this code, scan for the full code list — fixing the root cause usually clears multiple companion codes at once. If only P0692 is set without the companions, the issue is more isolated.
How do I prevent P0692 from coming back after a repair?
For P0692 (Fan 1 Control Circuit High), prevention centers on the cooling system. Service cooling system at OEM interval. Use the correct coolant type — modern HD engines need ELC (Extended Life Coolant), not green/conventional. Pressure-test cap and system annually.