Service light/ fault code diagnosis

[hairgoneJohn]

Hi

I’ve bought a 2012 DS3 1.6Hdi and can’t extinguish the Service light on the dash. I also get an engine fault warning on the display screen.

The start-stop doesn’t work and I don’t want it to work but is that the problem causing the Service light? Replacing the Super capacitor is expensive and then I’d need to find another way of avoiding the start/stop and all the wear it causes.

The fault codes on Diagbox are shown below. I don’t know what codes P1403/P1404 additional heat command refer to but have read that they can often be ignored.
Could any of you help with either the meaning of the additional heat command or which of the codes will likely be causing the Service light?
As an aside has anyone found a start/stop delete cable that fits a DS3 please?

Thanks for your help.

ps. Ive posted here rather than the DS forum as there are more of you here and I suspect the issue is not specific to DS.

BMF : Built-in systems interface
Response data
R61809664058780000696669522800604FFFF144052114799
R61B1940404A0302000002421240000
R61BA1200000000000000
State of the ECU: BSI
Reference 1 : 9664058780
Reference 2 :
Faults present : 1
F5FF : Unexpected re-initialisation fault coming from the BSI.
Characterisation : not characterised
Status :
Location : local
Variables associated with the fault

AFFICHEUR :
Response data
State of the ECU: communication error
Reference 1 :
Reference 2 :
Faults present :


INJ : engine management ECU
Response data
R61FEDF1C0000034102010C0915B20502010CFE02000001788961
State of the ECU: EDC17C10_BR2
Reference 1 : 788961
Reference 2 :
Faults present : 6
P1A9C : power accumulator
Characterisation : Energy accumulator state of health fault
Status : permanent fault
Location : local
Variables associated with the fault
engine coolant temperature : 067 °C
Engine speed : 0000 Rpm
Pressure in the rail : 0001 bar
turbocharging pressure : 1020 mBar
vehicle speed : 000 kph
Inlet air temperature : 028 °C
atmospheric pressure : 1010 mBar
battery voltage : 12.70 V
Vehicle mileage when the fault appeared : 0 km
Status of engine : cut off stalled
Voltage at the terminals of the power accumulator : 22.50 V
Power accumulator voltage reference value : 005.00 V
Power accumulator recharging current reference level : Reference value zero
Status of the voltage retaining device : voltage retaining device faulty
State of health of the power accumulator : 000 %
Temperature of the electronic unit of the voltage maintaining unit : -009 °C
Level of functionality of the voltage maintaining unit : voltage retaining device faulty
Measured temperature of the power accumulator : 024 °C
Pedal position consolidated : 000 %

P1403 : Additional heating 1 command
Characterisation : open circuit or short circuit to positive or short circuit to earth
Status : intermittent fault.
Location : local
Variables associated with the fault
engine coolant temperature : 037 °C
Engine speed : 0000 Rpm
Pressure in the rail : 0000 bar
turbocharging pressure : 1020 mBar
vehicle speed : 000 kph
Inlet air temperature : 035 °C
atmospheric pressure : 1010 mBar
battery voltage : 12.28 V
4 of 10 06/11/2025 12:59
Vehicle mileage when the fault appeared : 0 km
exterior temperature : 004 °C
Control of the additional heating relay 1 : inactive
Control of the additional heating relay 2 : inactive
Pedal position consolidated : 000 %
Status of engine : cut off stalled

P1404 : Additional heating 2 command
Characterisation : open circuit or short circuit to positive or short circuit to earth
Status : intermittent fault.
Location : local
Variables associated with the fault
engine coolant temperature : 037 °C
Engine speed : 0000 Rpm
Pressure in the rail : 0000 bar
turbocharging pressure : 1020 mBar
vehicle speed : 000 kph
Inlet air temperature : 035 °C
atmospheric pressure : 1010 mBar
battery voltage : 12.28 V
Vehicle mileage when the fault appeared : 0 km
exterior temperature : 004 °C
Control of the additional heating relay 1 : inactive
Control of the additional heating relay 2 : inactive
Pedal position consolidated : 000 %
Status of engine : cut off stalled



P16B4 : ECU
Characterisation : Error of plausibility of the signals for the Stop and Start function (Safety level
2)
Status : intermittent fault.
Location : local
Variables associated with the fault
engine coolant temperature : 037 °C
Engine speed : 0000 Rpm
Pressure in the rail : 0000 bar
turbocharging pressure : 1020 mBar
vehicle speed : 000 kph
Inlet air temperature : 035 °C
atmospheric pressure : 1010 mBar
battery voltage : 12.26 V
Vehicle mileage when the fault appeared : 0 km
Status of engine : cut off stalled
Voltage at the terminals of the power accumulator : 21.88 V
Power accumulator voltage reference value : 005.00 V
Power accumulator recharging current reference level : Reference value zero
Status of the voltage retaining device : voltage retaining device faulty
State of health of the power accumulator : 000 %
Temperature of the electronic unit of the voltage maintaining unit : -003 °C
Level of functionality of the voltage maintaining unit : voltage retaining device faulty
Measured temperature of the power accumulator : 050 °C
Pedal position consolidated : 000 %

U2000 : Intersystems CAN
Characterisation : Request for principal wake-up of the ECU not plausible or absent
Status : intermittent fault.
Location : distant
Variables associated with the fault
engine coolant temperature : 037 °C
Engine speed : 0000 Rpm
Pressure in the rail : 0000 bar
turbocharging pressure : 1020 mBar
vehicle speed : 000 kph
Inlet air temperature : 035 °C
atmospheric pressure : 1010 mBar
battery voltage : 12.26 V
Vehicle mileage when the fault appeared : 0 km
Pedal position consolidated : 000 %
Status of engine : cut off stalled
Main relay status : active
Status of the power relay : active
Positive ignition on status : ignition positive ON
Minimum voltage of the battery during starting : 09.0 V

U1213 : Intersystems CAN
Characterisation : One of the parameters present in a datastream sent by the ABS/ESP is
invalid
Status : intermittent fault.
Location : distant
Variables associated with the fault
engine coolant temperature : 026 °C
Engine speed : 1524 Rpm
Pressure in the rail : 0633 bar
turbocharging pressure : 1020 mBar
vehicle speed : 026 kph
Inlet air temperature : 014 °C
atmospheric pressure : 0980 mBar
battery voltage : 14.74 V
Vehicle mileage when the fault appeared : 0 km
Pedal position consolidated : 025 %
Status of engine : Pedal pressed
Main relay status : active
Status of the power relay : active
Positive ignition on status : ignition positive ON
Minimum voltage of the battery during starting : 08.3 V

[hairgoneJohn]

For those seeking the meaning of the P1403/1404 codes I've just found an interesting thread. Look at the post near the bottom with the wiring diagram

https://citroenc3owners.com/viewtopic.p ... tent=zid-1

It would appear that there are electric heaters within the heater matrix that provide instant cabin heat in cold weather.