No speedo or power steering Mk1 C3

[blackwrx]

Hi All.
I am working on my mothers old 2004 C3 hdi that has an issue with the speedometer not working and the power steering becoming heavy.
I did a search on and found a couple of similar issues. Both had replaced the speed sensor in the gearbox and but this didn't solve the issue.
They then cleared the codes and the speedo started working again and the power steering returned to normal. I had no means of checking the codes as I didn't have access to lexia so I replaced the speed sensor but this did not solve the issue. I then managed to buy a lexia set-up and managed to scan and clear the codes but it didn't solve my issue.I have an error in the power steering module and the display module both for "Vehicle speed incorrect value received" . I watched the data as I drove the car and the vehicle speed was staying at 0kph. Then after a minute it changed to 255kph and the steering becomes heavy. When I check the codes at this point I have a P0500 and a P0654 To get it to return to 0kph you need to turn the car off and remove the key. Then leave it for a minute and check the data again and the speed is back to 0kph.
Not sure where to go next. Any help greatly appreciated.

[GiveMeABreak]

You'll need to provide us with your VIN so we can provide the correct code info against the exact vehicle and systems.

The electric power steering provides assistance based on, amongst other parameters, the vehicle speed. A weak battery can also be a factor if the battery is older than 5 years old.

Please post your VIN in full without spaces - it will be automatically masked from public view after submitting your post & will only be visible to staff.

[blackwrx]

Hi. The VIN is VF7**************[VIN obfuscated, can be read by forum staff]

[GiveMeABreak]

Ok, so unfortunately there's very little this being a 2004 model - the fault data is very poor for this year.

The only thing I have is the obvious:

P0500: Vehicle speed data fault - Non Characterised.
P0654: Engine status information fault - Not Characterised

The following describes the situation where the assistance is reduced and how it works. Given the speed anomaly info you reported, it makes sense that the power steering is going into back-up mode. So you need to check the battery condition to make sure it is higher than 9V and then check the engine speed sensor.

This vehicle does not have ABS, nor ESP, so you won't have any wheel speed sensors. Therefore it will most likely use the engine speed sensor for this info, so I would be looking at this also.

1310 is the engine speed sensor shown below:

For the assistance motor to function, 2 conditions are necessary:

• Battery voltage higher than 9 volts
• Engine speed greater than 500 rpm

Backup Modes

The electric power steering ECU possesses a strategy for managing malfunctions appearing on the system:

• External to the steering (poor CAN communication, incoherent vehicle speed information)
• Internal to the steering system (torque sensor fault, cutting of an electrical circuit)

If one or more faults appear, the electric power steering ECU changes to back-up mode.
There are 2 types of back-up mode:

• Emergency assistance (assistance very much reduced)
• Total cutting of assistance

Faults	Back-up modes
Poor communication with the CAN network	Emergency assistance
Incoherent vehicle speed. Vehicle speed higher than 250 km/h. Absence of vehicle speed information	Emergency assistance
Engine speed/vehicle speed. Engine speed greater than 7000 rpm	Emergency assistance
Torque sensor malfunctioning	Total cutting of assistance
Battery voltage less than 7,7 volts	Total cutting of assistance
Assistance motor blocked	Total cutting of assistance
Cable problem	If the cable fault is detected prior to the starting of the engine, the power steering assistance is not ope

[blackwrx]

Thanks for the reply. I have already replaced the speed sensor and this did not change anything. It could be the battery as you say. I will check this tomorrow. It seems to be the "Incoherent vehicle speed. Vehicle speed higher than 250 km/h. Absence of vehicle speed information" situation as the speed reading on lexia goes to 255kph when the fault occurs.

[GiveMeABreak]

May be wiring in that case if you are sure the speed sensor has been replaced with a good known brand and nothing from ECP.

[modeslow]

Hello,
I see the post very “fresh” and willing some help too. My wife have C3 2004 1.4 16v SensoDrive with Start/Stop function. And it’s also disappearing and appears electric power steering. I'm wonder the vehicle already 20 years old and the most of mechanics and garages scratching their head pocking with finger to replace expensive parts. Once I’ve replaced electric power steering motor. Now started do again. I have an Autel and Lexia3 scanner tools. Autel cannot read even the VIN number but Lexia does. I have print screens with error codes which gonna post here bellow post. The car starts drive and fully shift gears with paddles and gear shift also even in manual mode. We are trying to save car ‘cos we both like so much how cheap and fun run. We bought travel to work and after. I suspect it gonna be transmission range sensor and probably need replace clutch actuator. But error codes stored in gearbox ecu, electric power steering ecu and ecu reversible stop-start alternator. Will upload pictures from Lexia. My iPhone doesn't let upload pictures. And I'm sorry for english.
C1400 - Fault not referenced in After Sales
P0654 - Fault not referenced in After Sales
P1702 - Temporary fault ECU power latch
U1221
U1209

Regards, Modestas