For several months, my 2008 Ford C-MAX 1.8 petrol with the Zetec engine and 65,000 miles has had an intermittent fault with the electrohydraulic power steering. A warning beep goes off and gives the dashboard warning ‘Power Steering Malfunction’, followed by the dashboard warning light going orange. The warning then goes away, but the amber light stays on. There is no change to the steering, although I think it sometimes changes itself to ‘Comfort’ mode. This warning occurs when you start the car or after 10-30 minutes. It does not seem to be connected with cold, heat, wetness, dryness, road gradient, braking or even steering, although it has been occurring more frequently and the warning nearly always comes on sometime during a journey. The fault is apparently not unique to my car and there are vague suggestions on the internet about it being due to the connector to the steering pump and an earth connection.
The vehicle is in excellent condition and free from rust. I don’t think it would be suffering from corroded connections, although I haven’t tried to clean these connections yet because access under the headlight is rather difficult. My village garage has no clue and I cannot find a power steering specialist near Cambridge.
When it first occurred, I topped up the sealed-for-life reservoir with about 70cc of Ford’s special oil, which seemed to keep it at bay for a few weeks. Mind you, I did not know how high the reservoir should be filled. Andrew Webb The light will illuminate when it detects a fault in the Can-bus system and should also retain a fault code, which should be retrievable using the Ford diagnostic system. There are some simple checks that can be done using a meter and these do concern the integrity of the connections. Even though your vehicle may be in good condition, there may be corrosion within the electrical plugs.
As I am sure you have already discovered, the reservoir is easily filled once the offside headlamp has been removed. To access the pump, the undershield must also be detached. Once you have access to the unit, undo the electrical plugs and check the condition of the terminals, then using a continuity meter ensure the resistance is less than 5 ohms to the earth connection and that the voltage from the supply side is greater than 10V.
As you have also had to top up the steering fluid, I would carefully check for any leaks. I have seen these steering racks leak from the steering column shaft, allowing the fluid to be soaked up by the driver’s underfloor matting.