Citroen C4 from 2009 - AL4 fault P1167

[lancia58]

Hi,

While driving my C4 make year 2009 I got a gearbox ( AL4 ) fault P1167 "Automatic gearbox Pressure Regulation Fault". Using Lexia I read the oil pressure at idle. The measured pressure was 4.9 bar instead of the expected 8.9 bar. At the very moment the fault was triggered the symptom of the fault was a slight vibration of shifting from 1st gear to 2nd gear and the gearbox got into limp mode and stacked on 3rd gear, but this symptom the car drove well. Turn the car off cleared the fault but the vibration stayed. After the fault triggered I drove about 7 miles ( the fault triggered couple of times till I got home, turn the car off and on cleared it ). Next day when I wanted to drive to garage after driving 5 seconds since starting the car, the car wont move like the clutches are slipping. I know that the solenoids regulate the oil pressure and when a solenoid gets faulty the oil pressure is not regulated correctly.
I don't think it is a slipping clutch/s since at the very moment it happened but the vibration on gear shifting the care drove well. It all started the next day after not driving the car for a day and let it cool down.

Can it be that a faulty solenoid will cause this problem ? Can it be that at the very moment it happened the because the faulty solenoid was warm the gear still functioned ( with the vibration ) and after overnight when gear and solenoid got cold the car wont drive ? BTW even when the car is not move the fault is not triggered .

Thanks
Zohar

[mickthemaverick]

It could indeed be a solenoid problem, but it could also be a sudden loss of gearbox oil. I'd suggest a first move is to check the oil level and then go from there.

[lancia58]

If it is a sudden oil loss how comes that I was able to drive home ? Can the oil loss after I parked the car ?

Thanks
Zohar

[lancia58]

Hi

Any idea ?

Thanks
Zohar

[ozvtr]

Can it be that a faulty solenoid will cause this problem ?

There are two classic faults that cause the "pressure regulation" fault. One is the main pressure regulation solenoid valve and the other is the pressure sensor on the bottom of the gearbox.
9 times out of 10 it's the solenoid. If you can get readings from the pressure sensor that make some sort of sense, then it wont be the sensor. Typically, a faulty sensor just spits out garbage.

[lancia58]

Can it be that a faulty solenoid will cause this problem ?

There are two classic faults that cause the "pressure regulation" fault. One is the main pressure regulation solenoid valve and the other is the pressure sensor on the bottom of the gearbox.
9 times out of 10 it's the solenoid. If you can get readings from the pressure sensor that make some sort of sense, then it wont be the sensor. Typically, a faulty sensor just spits out garbage.

If the pressure sensor is faulty can it be the cause that the car will not move like a slipping clutch ? As I described in the post opening this thread I got the fault during driving and but the vibration on gear shift the car drove well . I was able to get back home and park the car. Next day the car drove for 5 seconds and then it will not move at all like the the clutch is slipping.
I have to add that I replaced the pressure sensor two weeks before I got the P1167 fault, The pressure sensor is not a genuine but from Meat & Doria a very good aftermarket part supplier

Thanks
Zohar

[ozvtr]

If the pressure sensor is faulty can it be the cause that the car will not move like a slipping clutch ?

In this case I don't think so. The sensor appears to be giving good data.
The clutches and the brakes in the gearbox are actuated by the pressure of the hydraulic oil. This pressure is regulated by the main pressure regulator valve. So high pressure oil comes off the oil pump to the Solenoid valve which regulates it down to the pressure required by the control module. If it doesn't provide enough pressure, the clutches and brakes wont hold.
The solenoid valve controls the pressure by modulating. That is; by switching on and off. If you put the car in D or R you can hear the valve buzzing over the sound of the engine!! So it's working VERY hard. That's why they fail so often.

I have to add that I replaced the pressure sensor two weeks before I got the P1167 fault, The pressure sensor is not a genuine but from Meat & Doria a very good aftermarket part supplier

Was the wiring damaged from road dross?

[lancia58]

Hi,


What will be the symptom in case there is no electrical contact between the gearbox ECU and the pressure regulating solenoid ?

Thanks
Zohar