Citroen C4 II (b7) 1.6Vti 120 Valvelift problem - please HELP

[Avetius]

Hi everyone. I'm new here.
I have a problem with the engine on my 2012 C4 II (b7) 1.6 120VTi, very similar to what Yewboy69 described in 2024.

In December I had to replace the battery that died due to the cold, and when I restarted I heard an alarm signal. I immediately stopped and realized I had driven for a minute with the PBGA connector left unplugged. I connected it right away, but since that day the car has no more power and doesn't turn over 2000rpm. The OBD reader reported problems with the valve lift and some other errors:
P1015 Variable valve lift system: Reference value in down-grade mode not reached
P1062 Variable valve lift system: Position regulation fault
P1078 Variable valve lift system: Electrical circuit temperature too high

The mechanic replaced the valve lift motor and the sensors around it, the car seemed to move better but after two days the problem returned, this time with more errors:
P1030 Variable valve lift system: Jamming of the system
P1067 Power supply to the variable valve lift system: open circuit

The errors can be erased but they return after a few minutes of driving and the engine continues to have no power. I bought the Lexia and did some testing of the Valve lift actuators. The relay works, you can hear it click, but the valve motor does not react to the test. The motor itself is working, I know this because I tried to connect it directly to the 12v and I can clearly hear it moving back and forth. But when it's connected to the ECU it gives no signs of life, with or without the engine running. I also tried changing the BSI but the problem remains.

I'm lost, I no longer have any idea where to look for the fault. Could it be the ECU? Can it be PBGA? Could it be some broken cable of the ones coming out of the PBGA? I have the wiring diagrams but I can't figure out how to power the Valve lift motor. On the diagram I can't find any fuses or relays associated with the Valve lift. Can you help me diagnose the problem? I don't want to go back to the mechanic because instead of finding the real problem they change components at random.
Any advice is highly appreciated!
Thanks in advance.

[mickthemaverick]

You didn't mention whether you had been into the repair section and told the system it has had a new battery fitted. After doing that it is then advisable to do a BSI reset following the procedure in the link below and then I think the ECU should learn the new batteries characteristics and function accordingly. Not sure if that is the case but worth a try!

viewtopic.php?p=601679#p601679

[PaulC5]

We had a 2015 C4 1.6 hdi that was not accelerating that well and it turned out the fuse unit on top of the battery was faulty. This was found by the dealer with a diagnostic and being still under warranty did not cost us anything for the repair. Not suggesting this is the case for you but something to check.

[Avetius]

You didn't mention whether you had been into the repair section and told the system it has had a new battery fitted. After doing that it is then advisable to do a BSI reset following the procedure in the link below and then I think the ECU should learn the new batteries characteristics and function accordingly. Not sure if that is the case but worth a try!

viewtopic.php?p=601679#p601679

Oh yes, they have been told about it. I'm not sure they did any resetting, but I did that on my own. I found the same link you mention, and repeated the operation for a dozen of times. By the way, in another forum someone was suggesting (after the very same operation) to drive the car, accelerating steadily to 4000rpm on each gear. First time I did it the car has lost all that little power it had gained during the costly repair. Using the FAP app I could clearly see how that value drops gradually, from about 4.7mm to 2.5mm. I guess it should be actively moving up and down, managed by the ECU, but it looked like the lifter is left uncontrolled and the engine vibrations are simply moving it in one direction. Now the value is steady on 2.23mm. Another suspicious data from the engine is related to the Air flow. The instruction value is changing in a wide range, but the measured air flow value is veeeery far from the instructed one. And I guess it has to do with the inlet camshaft dephaser, which I imagine should be moving too, but it is stuck on 119-120 degrees always. Is this normal? Is this anyhow connected to the valve lifter anomaly?

But, regarding your hint, I can see the point of instructing the new Valvelift motor for correct operation and optimal values, but I also wonder if the actuator tests, which you can run from within Diagbox tool with engine not running, should just move the valves up and down so to be sure that the command chain works flawlessly. Am I wrong?

[Avetius]

We had a 2015 C4 1.6 hdi that was not accelerating that well and it turned out the fuse unit on top of the battery was faulty. This was found by the dealer with a diagnostic and being still under warranty did not cost us anything for the repair. Not suggesting this is the case for you but something to check.

Hi PaulC5
Thanks for reaching out.
That's a very interesting testimony. That fusebox (BPGA) has figured in the very beginning of my trouble. The connector I forgot to attach was the one going exactly to the PBGA and I thought about it many times. The problem is part of that component can be easily checked (fuses), and another part (with electronics and some relays) is factory sealed. I intuitively suspected that everything could have started from that minute of drive with the connector detached, but I also can't get how on Earth that is involved in the management of the Valvelifter today. The Valvelift motor is physically wired to the ECU, and when I launch the actuator test from Diagbox, I expect the ECU to run the motor. From the Citroen diagrams there are no other elements on that path, but I see another actuator test, involving the Valve lift relay (which works, it was just very quiet!) and that tells me that there are more signal paths and more components involved in the Valve Lift operation than I can read on the diagram. If only I could understand the complete path of the current, from the battery down to the VL motor, I could check all the connectors, cables and relays. I can only guess that the ECU gets the voltage from somewhere, switches the polarity as needed and forwards it to the VL motor. Now the ECU tries to do that, opens the relay, but apparently the very current is missing, and I don't understand were else should it come from, if all of the fuses are OK and 12V enter all the cables, departing from the fusebox.
Well, I guess I could order that BPGA somewhere on ebay to make a test and see if that could be the reason.

[Avetius]

Some months later I'm still there with the problem. I asked to check my ECU but it turned to be healthy and now there are no components left to be faulty. The only suspect is that I'm doing the ECU learning wrong. Yesterday I tried to bring the VVL opening to it's minimum (by rotating the VVL motor from behind manually, with the help of an hex key). The result surprised me: now, during the start-up procedures on battery connection, I can clearly hear some short bursts of the VVL motor, as if the ECU would try to establish a connection. Before now the VVL motor has been always silent. And yet it didn't solve the issue, the VVL reinitialization procedure still doesn't bother moving the VVL motor at all and in this minimum valves position the motor refuses even to start running. I had to bring the valves over 1mm (manually) in order to start the engine again. I suspect the solution is just behind the corner. Probably there is a precise procedure to be done for the VVL learning to begin, a starting angle, or motor-sensor learning sequence.
Any hint anybody?