"Vehicle Communication Bus C" and hickups when driving (1.6hdi)

[Axa]

My 1.6hdi 2006 C5 have developed worryingly hickups while driving. The car starts and drives without any other issues, and it have only happened about 15times so far over about a week of driving. And mostly between 60 to 90kmh. Once while accelerating at lower speed.
Today it occurred 3 times within 1km.
OBD2 code U0046 "Vehicle Communication Bus C" is the only lead I have. EGR valve is blanked off..
Any ideas what I should look for?

[GiveMeABreak]

U0046 is a code returned when there is a fault with the Body VAN 2 network. I think this is specifically for the additive function, as you have a Diesel Particulate Filter fitted.

Unless you’ve removed the DPF with the EGR valve? If you have, we can’t really help as the car is designed to work with them and our advice is always to repair rather than remove which is generally illegal now for road use in the EU.

[Axa]

Hi Marc.
Unfortunately my drivingpattern does not work with DPF at all, and with the useless second hand value I can not afford to swap for a car that do at the moment. Also since millions of DPF cars have been sold without any information or warnings about this weakness, I really don't feel bad for braking this rule at the moment. This car have done close to 300,000km with DPF, and scrapping it in favour for a new car would cause far more pollution then keeping it going for a few more years. Also counts for buying an older non DPF car.. I hope I can afford an electric car one day to do what I can to keep our planet a bit cleaner. But up to then I have to prioritize to keep this C5 in best possible reliability so I can respond when the Fire&Rescue cervice needs a fool that tought it was a wise choice to buy a "clean" oil burner car...

Now moral aside. It does not really add up that this fault should be connected to DPF or Eolys. It happens before the engine gets up in temperature anywhere close to regeneration temperature.

[GiveMeABreak]

The issue is relevant, because the engine ECU is expecting those systems to be there and if they have been removed, then you have to expect errors. You didn’t mention if the DPF had been removed or not, but if it has, the car’s multiplexed systems expect to communicate with the various pressure sensors, the additive injection pump etc.

Another example being that when you refuel, the BSI and the engine ECU determine if any fuel has been added and if so, how much, to determine the amount of additive to be injected. If it can’t communicate with the additive pump or if any of the sensors are not functioning it will cause faults, and depending on the issue, the engine ECU will go into a backup mode.

[Axa]

Thanx allot Marc for that explanation!! Reading codes again a few others have appeared. The first two fits well into what you say:
P1435 Fuel aditative pump - Fault
P1445 DPF - Total aditative added supperior to maximum threshold
C1114-45 No description available
P0104 Mass or Volume Air Flow - Circuit Intermittent.

I have now cleared the codes and no codes appears when reading again after 5km drive.

Any suggesting on what I could check out should expect are greatly appreciated!

[GiveMeABreak]

Well these are the official explanations - You can check your Mass Air Flow Meter easily enough, but I think you know the reasons for the anti-pollution issues - expect messages if the components are missing..

P1435: Additive system : Additive system fault
Diesel fuel additive ECU (ADDGO) : Problem of communication on the CAN
Downgrade Modes: Deactivation of piloting of the additive pump from the particle filter;
Stopping of the cumulative calculation of the quantity of additive to be injected;
Deactivation of forced regeneration of the particle filter by the diagnostic tool
Suspect Area: Additive pump

P1445: Additive system: Quantity of additive remaining in the tank too great
The total quantity of additive injected is more than 80 g for 1 second
Suspect Area: Additive pump

P0104: Flowmeter signal : Open circuit or short circuit to positive or short circuit to earth
The ECU detects a short-circuit on the harness of the air flowmeter : Open circuit or short circuit to positive or short circuit to earth (For 1,2 seconds)
Downgrade Modes:

• The ECU uses a replacement value for the air flow
• Deactivation of the coherence faults of the flowmeter
• The ECU cuts the regulation of the EGR valve
• The ECU cuts the regulation of the bypass mixer

Suspect Areas:

• Lack of power
• Air flow meter
• Electrical harness Connectors

[Axa]

Is it possible to find out what number 28 in code P0104-28 stands for?

[GiveMeABreak]

That is a generic code reader - some of the codes like that C1114 are not valid for your car and neither are the ones with the extra numbers:

viewtopic.php?f=51&t=59824#p571421

I suspect your code reader can't interpret the data properly, but the extra numbers don't have anything to do with PSA codes.