Skip to content
Skip to content

OBD-II Code

P0691

Severity

Not yet reviewed

Nobody on our side has assessed this code yet, so we are not going to guess at how serious it is.

Can you drive it

We cannot say

Treat it as unknown until a shop reads it with live data. If the check-engine light is FLASHING, stop driving as soon as it is safe to — that means an active misfire, whatever the code.

Indicative cost (USD)

$35–$480

From this code's diagnostic notes. Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.

P0691 means the PCM detected the Fan 1 control circuit pulled low when it should not be, or the low-side driver is reporting under-voltage on the cooling fan 1 output.

How a shop works this

Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.

  1. Note every code that is set, not just this one.

    Codes that appear together usually narrow the cause faster than any one of them read alone.

  2. Read the freeze frame — the conditions the fault was recorded under.

    Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.

  3. Confirm the fault is current rather than history.

    Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.

  4. Then follow the diagnostic notes further down this page, in the order they are written.

    They are written in the order a shop works this code, cheapest checks first. Where they name a component, inspect its wiring and connector before replacing it.

If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.

Common symptoms

  • Check engine light
Read the full diagnostic procedureP0691 means the PCM detected the Fan 1 control circuit pulled low when it should not be, or the low-side driver is reporting under-voltage on the coo…

P0691 means the PCM detected the Fan 1 control circuit pulled low when it should not be, or the low-side driver is reporting under-voltage on the cooling fan 1 output.

Cheapest-first ladder

  1. key-on engine-off, unplug the fan 1 relay or fan control module connector and measure resistance across the relay coil (typically 50 to 90 ohms) or the FCM low-side driver pin to ground (should not be a dead short).
  2. With the connector unplugged, the PCM control wire to the relay/FCM should sit at battery voltage (about 12.6 V engine-off, 13.8 to 14.2 V running); 0 V at this point points to a wiring short to ground between PCM and relay, which is the most common P0691 cause.
  3. Reconnect and command the fan on with a scan tool; on a healthy single-speed setup you should see 0 V on the control wire when commanded on (PCM is pulling it to ground) and battery voltage when commanded off, with fan current draw between 8 and 25 A momentary inrush settling to 3 to 12 A steady, and less than 0.3 V drop across the fan power feed terminal under load.
  4. On PWM-controlled fans (Ford F150 5.0 Coyote, GM 6.2 L86) watch duty cycle on the scan tool ramp from 0 to 100% as commanded ECT rises from 200 to 235 F. Expensive-misdiagnosis caveat: fan resistor packs are the common consumable on multi-speed fan systems.
  5. Ford, GM, and Toyota all use 3-step fan resistor packs (low/med/high) that burn open at the high-current stage from heat-cycling at the soldered tab; the fan itself runs fine on low and medium, the PCM commands high, sees no current flow, and sets P0691 or P0693.
  6. Replace the pack ($40 to $120), not the whole fan assembly ($250 to $600).
Vehicle-specific patterns2011-2014 Ford F150 5.0 Coyote uses a PWM single-fan setup through the FCM-A relay/module mounted on the radiator support; the FCM-A solders to its o…
  • 2011-2014Ford F150 5.0 Coyote uses a PWM single-fan setup through the FCM-A relay/module mounted on the radiator support; the FCM-A solders to its own pigtail and the solder joints crack from underhood heat, setting P0691 intermittently when the connection opens; Ford supersession is a redesigned FCM with crimped terminals, $150 to $260 installed.
  • 2007-2014GM Silverado/Tahoe/Yukon with the 5.3/6.0 use a clutched primary fan plus an electric secondary fan; P0691 on these is almost always the electric secondary relay (mounted in the underhood fuse block) or its low-side driver shorted to ground after a coolant leak from the upper hose dripped onto the relay block, $35 relay swap.
  • 2007-2017Toyota Camry V6 (2GR-FE) runs a dual electric fan with a 3-step resistor pack riveted to the fan shroud; P0691 here is the pack 80% of the time, $50 to $90 part.
  • 2006-2015Honda Civic/Accord with the single PWM 1A or 2A fan throws P0691 from chafed fan-motor harness where it routes past the radiator support bracket, repair the chafe and the code clears without parts.

Estimated repair$35 to $480.

Look up another code

More free tools

VIN DecoderDecode year, make, model, engine, recalls.Maintenance ScheduleOil, timing belt, fluids, by vehicle.Tire SizeOEM vs new — diameter delta + speedo error.Gas CostWeekly, monthly, annual fuel math.

See all 9 tools