P0693
PowertrainCooling Fan 2 Relay Control Circuit Low
Most cars with a big air-con system or a thirsty engine run two radiator fans, and this code is about the second one. The relay or wiring that feeds that fan is reading a low voltage on the control side when the ECU expects it to sit clean and quiet. The module flags P0693 because it can't trust the circuit, and if the fan won't kick in when it's wanted, the engine can run hot in slow traffic or on a warm day with the air-con hammering away.
ⓘ Information only. This page provides general educational information about fault code P0693. We do not assess the urgency or safety implications of any specific fault. That requires in-person diagnosis by a qualified mechanic. Full terms.
Recommended next steps
Whether a fault is urgent, drivable, or routine depends entirely on the cause on a specific vehicle, and that can only be determined by a qualified mechanic with diagnostic equipment. If a warning light is illuminated, the most reliable next step is professional diagnosis.
What does P0693 mean?
P0693 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Cooling Fan 2 Relay Control Circuit Low.
This is a standardised OBD-II code. The technical definition is the same regardless of the make or model of vehicle, although specific causes and symptoms can vary between vehicles.
Symptoms commonly associated with this code
Symptoms that drivers often report alongside this code. Not all may apply to every case:
- • Engine warning light on, usually with no obvious drama at first
- • Temperature gauge creeping up when you're stuck in traffic or queuing on a hot day
- • Air-con going lukewarm at idle or in slow crawls, then picking up once you're moving again
- • Second fan never spins, even when the engine is well up to temperature
- • On some cars the temperature warning light comes on if it gets bad enough
- • Fan that runs in short bursts then cuts out
Possible causes
Causes commonly associated with P0693, listed in approximate order of typical investigation. The actual cause on a specific vehicle can only be confirmed by professional diagnosis.
- 1. Blown fan circuit fuse. Cheapest and most common starting point, so always look here before anything else
- 2. Sticky or burnt-out fan relay. These cook themselves over years of switching and are a frequent culprit
- 3. Corroded or chafed wiring in the fan control circuit, often where the loom runs near the front of the car and cops road salt and water
- 4. Loose or green-with-corrosion connector at the fan or the relay base
- 5. Failed secondary fan motor that's drawing wrong or no current and confusing the circuit
- 6. Coolant temperature sensor feeding the ECU duff readings so it never commands the fan properly
- 7. PCM fault, which is rare and the last thing to suspect
How mechanics typically diagnose
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 all stored codes and read them together. A P0693 sitting next to a coolant temp or other fan code tells you a lot about where to dig first
- 2. Check the cooling fan fuse. If it's blown, fit a new one and watch it. A fuse that pops straight away means you've got a dead short to find, not just a tired fuse
- 3. Have a proper look at the fan wiring and connectors. Unclip them, check for corrosion, water, melted plastic or chafing where the loom rubs the body
- 4. Swap the fan relay for a known-good one of the same part number. Half the relays in a modern fusebox are identical, so you can borrow one from a non-critical circuit to test
- 5. With the ignition off, give the fan blades a spin by hand. If they're stiff or seized, the motor is your problem, not the relay
- 6. Get the engine up to temperature and back-probe the fan control connector. You want to see roughly 11.5 to 12.5V when the ECU commands the fan on. No voltage points upstream, voltage but no fan points at the motor
Common questions about P0693
How do I work out whether it's the relay, the wiring or the fan motor itself? +
Start at the cheap end and work up. Check the fuse first, then swap the relay for an identical one. If the fault clears with a new relay, you're done for a couple of quid. If it doesn't, back-probe the control connector at the fan with the engine hot. Got 12V there but the fan still won't turn? It's the motor. Got nothing at the connector and a good fuse and relay? Then you're looking for a break or corrosion in the wiring between the relay and the fan, which is the most time-consuming of the lot to track down.
Can I sort this on my own driveway, or do I need a garage? +
The fuse and relay checks are fair game for anyone with a fusebox diagram and ten minutes. A new relay is usually under £20 and the fuse is pennies. Where it gets harder is testing the circuit live and replacing the fan motor, because the second fan often sits low and tight behind the bumper or rad, so you'll need to lift the car and may have to drop the front slam panel or undertray to reach it. If your multimeter testing points at a buried wiring fault, most people hand that to a garage rather than spend a weekend chasing a chafed wire.
If I just clear the code, will it stay gone? +
If the real fault is a blown fuse or a knackered relay and you've replaced it, clearing the code is the right move and it'll stay off. If you wipe it without fixing anything, it comes straight back the next time the ECU runs its fan check, usually within a drive cycle or two. A code that keeps returning after a fuse swap means there's a short somewhere pulling that fuse down, and that needs finding before the fan will work reliably.
Information only, not professional advice
The information on this page is provided for general guidance and educational purposes only. It is not a substitute for diagnosis or repair advice from a qualified mechanic. Always verify any fault before paying for repairs. carfaultcodes.co.uk accepts no liability for decisions made based on this information. Full terms →