How is fault code P0691 fixed?

A typical diagnostic sequence used by mechanics, provided here for educational reference only. Diagnostic work should be performed by a qualified mechanic with the appropriate tools and training. 1. Pull the codes and check the freeze-frame data for what the engine was doing when it logged. Note any other fan-related codes sitting alongside it 2. Check the cooling fan fuse for a blown element or heat discolouration. A blown fuse points you straight at a short or a binding motor 3. Swap the fan relay with an identical one from another circuit and see if the fault moves with it. Cheap, quick, and rules the relay in or out 4. Back-probe the control wire at the relay with a multimeter while commanding the fan on with a scan tool. Low or no voltage here tells you whether it's the ECU side or the relay side 5. Go through the wiring and connectors with a torch, looking for green corrosion, melted insulation, or pins backing out of the plug 6. Spin the fan blades by hand with the ignition off. If they're stiff or grind, the motor's on the way out and it'll keep eating fuses

Fan 1 Control Circuit Low

Jump to the fix

Severity

Medium

Can I keep driving?

Usually drivable, but get it diagnosed without delay.

First step

A typical diagnostic sequence used by mechanics, provided here for educational reference only. Diagnostic work should be performed by a qualified mechanic with the appropriate tools and training. 1. Pull the codes and check the freeze-frame data for what the engine was doing when it logged. Note any other fan-related codes sitting alongside it 2. Check the cooling fan fuse for a blown element or heat discolouration. A blown fuse points you straight at a short or a binding motor 3.

PPowertrain
0Generic code
6Computer Output
91Sequence number

What does it mean?

If you have gotten this code, it means the cooling fan, which is located on the backside of the radiator, is inoperable. This is caused by one of two things. Either the fan works but does not work as well as it should; or the fan is not in working condition. The reason this code happened is because the ECM or Engine Control Module, has detected that the voltage has dropped to the bottom 10% of the parameters set by the manufacturer. When it gets that low, it will send a code, warning you of the drop.

Symptoms

Likely causes

How to fix it

Codes From the Same System

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This information follows the generic OBD-II definition and does not replace a vehicle-specific diagnosis. The severity rating is rule-based; an authorised diagnostic reading is required for a definitive answer.