Technical Fault code P0190 and P1620

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Technical Fault code P0190 and P1620

Alan: You do not by chance have any wiring diagram for the LPG control unit "laying around", or the possibility to tell me which pins are connected to the pressure sensor?
 
I checked the wires from the pressure sensor to the LPG control unit.
PS Blue/Red (ground) to pin 6 on control unit.
PS Blue/Green (signal) to pin 30 on control unit.
PS Red/Green (supply 5V) to pin 16 on control unit.
All of the are ok.

ECU-pins.jpg

I then cut the Blue/Green signal wire from the pressure sensor and meassured the voltage. (0,15V)

Pressure-Sensor-measure.jpg


There is NO LEDs lightning on the LPG control panel.

LPG-LED.jpg

Reading the OBD fault codes again I get P0190 and P0191:

error3.jpg


I think the conclusion must be that the pressure sensor is "shot" or am I missing something?
 
Hi,

Was the 0.15v reading with the ignition at MAR? If so then it is outside the range of performance. It should be 0.5v minimum when the tank is empty.

Also, when you turn the key to MAR, all if the LEDs on the LPG selector switch should light up for a few seconds. (Self test) is this happening?

From my point of view it's certainly looking like the pressure sensor may be faulty, however they are very expensive so best to check all possibilities. It was indeed my initial suspicion from your first description.

Another quick test you can do is to electrically disconnect the pressure sensor, turn the key to MAR and check with your diagnostics equipment if any further DTC's are detected. Also on EXaminer/ Witech you can view the live reading from the sensor, I'm not sure if your diagnostic equipment can do this, but if it can it's also worth a check just to double confirm what the ECU is seeing.

Nice photos by the way (y)

Alan
 
[FONT=&quot]1. The 0,15V reading was with the ignition at MAR.
2. When I turn the key to MAR, all the LEDs on the LPG selector switch are on for a few seconds.

Self-test-start.jpg

[/FONT][FONT=&quot]After a few sec. it look like this:


Self-test-end_pg.jpg



[/FONT][FONT=&quot]3. I've not the possibility to read life sensor signals from the ECU.
4. When I disconnect the pressure sensor, turn the key to MAR and check with my diagnostics equipment no other DTC's are detected.

Do you think it would be ok to take the 5V supply (on the pressure sensor) and feed it to the signal cable via diodes to reduce the supply from 5V to 4V?

Simulate-sensor.jpg
[/FONT]
 
Hi mate,

Good, the self test is all functioning as it should. I don't see any reason why you couldn't do as you say for quick TEST purposes without removing the sensor. Obviously it would need to be below the 4.5v threshold otherwise it would pull the same fault for "circuit high".

If the gas level LEDs change then you know that it's the sensor giving a false reading.

Alan
 
My test with diodes worked out fine.
I connected 4x 1N4004 diodes in series, connected it to the signal cable (Reduced the voltage to 3,75V) and turned the key to MAR.

Simulate-sensor_2.jpg

DTC P0190 disappeared but P1620 is still there and P1658 is a new one.
P1658 - Gas injectors relay

Where can I find the relay?
 
Good news!

After struggling with different DTC's I tried out Multiecuscan. It is really a nice piece of software.
Using Multiecuscan I was able to check the relays, pressure sensor, petrol/LPG switch and many other parts.
Now I am able to run the car on LPG and petrol but there is still one fault code left (P0191- Pressure on injector support /Signal high/Fatal/Light ON).

Does anybody have any idea?
 
Finally it passed MOT. (y)

P0190

Possible causes
- High fuel pressure
- Low fuel pressure
- Damaged FRP sensor
- Excessive resistance in the circuit
- Low or no fuel
- Wiring harness connector of the fuel pressure sensor
- Fuel Rail Pressure Sensor
- Vacuum leaks
- Fuel

The cause for the fault code was the wiring harness connector on one of the gas bottles.
 
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