C4 (B7) Various Issues

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cenk
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C4 (B7) Various Issues

Post by cenk »

hi lenny,
i just saw your topic and i have same DTCs, but i have no EPB :?
did you solve the problems?
i opened a topic about my DTCs and complaints
viewtopic.php?t=65921
could you help me, please?
thank you.
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Re: C4 (B7) Various Issues

Post by GiveMeABreak »

You can't have those same codes if you have a manual parking brake, as they relate to the Electronics for the electric handbrake system which a manual handbrake does not have.
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Re: C4 (B7) Various Issues

Post by cenk »

really? oh my god :oops: could previous owner take another car's ECU that have EPB? :cry:
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Re: C4 (B7) Various Issues

Post by GiveMeABreak »

The electronic parking brake has an ECU withing the Handbrake unit, but is controlled by the ESP ECU in a master - slave relationship. So the ESP ECU tells the EPB what to do, as it needs to tell the EPB when to release and apply the handbrake and other features such as hill start assistance etc.

The manual handbrake is purely mechanical.

Put you VIN up here so I can see what exactly you have on your vehicle as it left the factory.

It is not practical to put an EPB on a car without one as there are far too many changes to be made, not least to the centre console and all the programming.

What may of happened is that somebody has been fiddling with Diagbox and changed some settings which can cause fault codes if the ECU is not actually there when it has been configured as having one.
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Re: C4 (B7) Various Issues

Post by cenk »

Thank you very much for your interest in my issue,
my VIN is VF7**************[VIN obfuscated, can be read by forum staff]
I would be verrrryy happy if you could help [-o<
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Re: C4 (B7) Various Issues

Post by GiveMeABreak »

Ok, so you actually have a C4, not a C5 X7 (which this thread is specifically concerned with).

But confirmed, you have a manual parking brake. There were some of these C4 B7 models with an electronic parking brake, but it was a different system. So I do not know where these codes are coming from unless for the reasons I already mentioned in my last post. :wink:
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Re: C4 (B7) Various Issues

Post by cenk »

thank you so much Marc, sorry that you had a problem with your car, hope you can handle it easily,
I can wait, I will be glad if you can look up in your free time.

ok, here we go,
seller said: it was a disabled car and converted it to normal.
Has LPG system on it.
I just decatted it. p0054 fault code after decatting, read with my elm327 obd2 tool.
steering wheel is hard to turn.

in Neutral: I can rev it to highest rpm easily when press to gas pedal.
my main complaint is (since i bought the car) : lack of power, high fuel consumption, straight road acceleration is sluggish, slowing down when going uphill even if pressing the accelerator nearly to the floor, it doesn't increase revs but instantaneous fuel consumption very high(20-30 liters/100km).
when I press down to kickdown switch, gearbox changes down and increases revs and acceleration is more satisfying but fuel consumption very high(25-30 liters/100km) I can't drive like this all the time.

my VIN: VF7**************[VIN obfuscated, can be read by forum staff]

my fault codes at Citroen Authorised Repairer Diagbox:
al4 (at8) auto gearbox : U1003
engine ecu : U2000, U2118, P0420
abs : U2000, U1318, C1510

and with a multidiag like tool shows:
BSI: : B162C (accesories positive relay control and status not coherent)
Airbag : B0001 ( airbag light on, sometimes off, loose contact i think)
U1802 (error in vehicle speed signal - invalid data received)

Transmission : P1167 (Pressure Regulation Fault: intermittent) this is new

integrated controlled steering wheel (VCI) : U1F1A ( lin bus )
: (Fault event not stored in the faults log)

Radio : B1501 (front left audio output fault)
: B1502 (front right audio output fault)

what does these fault codes stand for, any TSBs for them?
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Re: C4 (B7) Various Issues

Post by GiveMeABreak »

I'm not so sure removing the cat was wise - if you are using dual fuel it may still be a requirement to pass the inspection - even in Turkey. So I can't help you with that - and would suggest you put it back.

I think you have a wider problem with something you've done - especially on the CAN network. A lot of these codes are related to CAN communications, so my question would be have you made any wiring modifications to the vehicle / cut any connections or anything like that? If you've cut any CAN wires you will have lots of problems as the various ECUs won't be able to communicate along the data network.

U1003: CAN communication fault (Missing/interference): No signal / Automatic transmission control unit: Mute
Fault will disappear when the CAN bus is active again.
Symptoms: Lack of power, Deactivation of the speed limiter, Deactivation of the cruise control, Difficult/impossible to change a gear.
Downgrade Modes Whilst Fault is Active: Absence of pressure regulation, No lock-up control, Absence of control of Neutral when cold (Absence of engine starting assistance in low temperatures), Control: Flow control solenoid in the exchanger (According to turbine speed), Coolant temperature = The oil temperature, Absence of autoadaptation for the controlled sliding of the converter, No engine management ECU switch to dormant mode phase (Complete switching off of the networks), No management by the ESP, Change from position N to a forward gear impossible, Change from position N to a reverse gear impossible, Absence of detection of locking of wheels.
Suspects: Main harness, Automatic transmission control unit, Built-in systems interface.

U2000: CAN network: Main wake-up fault - Main wake-up status absent (CAN information absent and/or invalid request sent by the BSI).
Downgrade Mode: The engine ECU changes to "down-grade principal wake-up" mode.
Suspects: Built-in systems interface, Engine ECU

U2118: Same as above: Detection of an anomaly on the request for partial wake-up status (CAN network disconnected; Short-circuit on the CAN High/CAN Low line; Loss of information on the CAN network).
Down Grade Modes: Exit from partial wake-up and change to transitory mode, Change to internal partial mode followed by extinction of the engine ECU (Provided no new request for wake-up of the BSI has appeared).
Suspects: Built-in systems interface, Engine ECU

U1318: CAN network: Communication fault with the BSI ECU. Loss of a certain number of consecutive safety values sent by the BSI (Battery charge status; Battery temperature; Type alternator control).
Fault Triggering: The following conditions have to be met:
  • - Presence of a BSI
  • - No CAN fault on the engine management ECU
  • - Engine management ECU in "main triggering" or "down-grade main triggering" phase
Suspects: Engine ECU, Built-in systems interface.

P0420: Catalytic converter: Loss of effectiveness. Catalytic converter ageing: Catalytic converter oxygen storage capacity value less than a threshold (For 6 test cycles).

You know why this fault is showing - given you have removed the cat...
Downgrade Modes: Transition to open loop of the downstream regulation' Deactivation of the canister purge function.
Symptoms: Emissions outside the norms, Reduction in engine performance
Suspect: Catalytic Converter

C1510: Fault Not Characterised.
U1318: Fault absence of communication with the built-in systems interface: No signal. Incoherent data coming from the built-in systems interface, so basically all extra functions (Hill Start / Auto mode) of parking brake are none-operational.
Suspects: CAN Network. ESP ECU, BSI

P1167: Pressure regulation fault (Difference / reference value): Not characterised. Pressure fault with a gear engaged (Excessive pressure error or the autoadaptive correction is saturated).

Symptoms: Lack of power, Deactivation of the cruise control, Deactivation of the speed limiter, Difficult/impossible to change a gear, Leaks.

Down Grade Mdes: Refuge mode, Line pressure forced to 21 bars, No declutching on stopping.

Suspects: Automatic gearbox (BVA), Electrohydraulic block, Fluid level, Electrical harness of the hydraulic valve block, Main harness, Oil pressure sensor, Automatic transmission control unit.

Audio / RD5
B1501 / B1502: Basically, short circuit to either earth or positive - though there are 2 digits missing from the end to I can't tell you which it is. (B1501 11 - Earth or 12 Positive)
Same for B1502

The U1F1A is a short circuit on the LIN 1 network.

So most of these issues are related to the electrics - whatever has been done when you decatted / installed the LPG has had an adverse condition on the vehicle operation. So assuming none of the ECUs have been fried, I suggest you start retracing steps and checking all electrical connections - especially to the BSI.
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Re: C4 (B7) Various Issues

Post by cenk »

Hello Marc,
thank you very much for the invaluable information you gave,
yes, the owner before me had the interior lighting in the footwell,
they are on when the interior lights are on too.
maybe a mistake was made during installation and this has affected the BSI,
I will ask electrician to take a look at the BSI and wiring.
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Re: C4 (B7) Various Issues

Post by GiveMeABreak »

Basically, with modern multiplexed vehicles, a lot of the electronic control units are connected by several data networks - so if you break these wires or cut them / bypass them, then you are cutting off communication and nothing works properly. It's never a good idea to hack the vehicle wiring or cut into the wiring. Always run new wiring to the fuse box or BSI using a piggy back fuse if you need to power third part accessories.

Best of luck, but remember that a lot of the ECUs rely on getting information from each other for the related systems, so if it is missing they will fail or go into reduced performance mode.
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Re: C4 (B7) Various Issues

Post by cenk »

Hi Marc,
i had my car's BSI checked last month, and a new cat installed last week, but lack of power still the same,
a few days ago went to an authorized service and they said that many important and expensive parts of the engine needed to be replaced, including engine ecu and engine wiring harness loom,
i got a copy of the report and saw the following DTCs in airbag section

B0001 1B
U1802 81
U1F00 00
B00D2 67
B00D5 67

i think these errors are not important except U1802 81
i googled it and means vehicle speed signal invalid
my theory is: (due to wiring) signal from the abs ecu confuses engine and transmission ecus and also if speed signal is high, this causes steering stiffness.
could you look up this error code please, is there any detailed info about the dtc?
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Re: C4 (B7) Various Issues

Post by GiveMeABreak »

I've split this off into a new topic as the issues are for a different vehicle with different problems... I will take a look at the codes shortly.
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Re: C4 (B7) Various Issues

Post by GiveMeABreak »

So this is the descriptor for the 1802 81 fault: So the CAN network is not providing a proper value or the BSI is shot - but given that I think we have established from previous posts on the other thread before I merged it - you have said you cut the CAN wiring somewhere - so this is where I would be checking first.
Fault Code: U1802 81
Description of Fault:The "vehicle speed" parameter takes the value "invalid value" on the CAN for more than 2 secs. The fault is active when: - Ignition is on
- Vehicle is not in economy mode
Conditions for Fault to clear: The "vehicle speed" parameter takes the value "valid value" on the CAN for more than 2 secs
Downgrade Modes whilst Fault is active:Display of the speed replaced by "--"
The speed indicator displays 0 km/h
Symptoms: Absence of display, or wrong display of information
Suspect Areas: Built-in systems interface
Multiplexed network
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Re: C4 (B7) Various Issues

Post by cenk »

Thank you for everything Marc, you're the man,
I'll update if I can succeed :wink: