Hi.

Engine stopped running due to what I belive to be contaminated fuel.

I've got new injectors. Coded them

I've got fuel going to them, and returning.

But there not pulsing.

Tried crankshaft sensor also

P009b is a code I'm getting - fuel pressure relief control - circuit open

I belive this is the issue..

There's 2 sensors on the rail
1 on fuel pump

(I've got a new fuel pump coming)

Any ideas where to to turn. So I'm not replacing everything

You've already replaced far more than is needed. I wouldn't have replaced anything without checking the codes.
The pressure relief is on the pump end of the rail. Just check it with a multimeter for resistance, which should be a few ohms. Anything more and it needs replacing. Hyundai Ioniq 5 Ultimate. The family car.
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Audi A5 convertible, my daily driver.
1972 Hillman Avenger GT, the project.

I had the injectors tested. And they failed, hence the replacements

Fuel pump I've got just incase lol.

Do I test the wireing to the sensor or the sensor itself?
Is this with key in dash or makes no difference.

Thanks for the reply mate.

I'm curious as to how the injectors were tested. These injectors are extremely durable and seldom suffer issues, especially effecting all 4 of them.

You can check the pressure regulator by pulling the plug and probing the pins directly.
I'd be cautious about checking the harness at the ECM, as it's very easy to damage the plug, which will only add to the pain.
You can check the harness by probing the plug at the sensor on resistance, with the ignition off. You should get a reading of some sort maybe several k Ohms. If the readings are into M Ohms, then suspect an issue with the harness or the ECM, although the latter is unlikely. Hyundai Ioniq 5 Ultimate. The family car.
2009 Rimini Red SE TD4. Gone.
2006 Tonga Green i6 HSE. Gone.
Audi A5 convertible, my daily driver.
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fuel pressure outside of threshold will stop injectors for engine safety.
i would be looking at fuel rail pressure control , as it says open circuit, however has this just been unplugged and caused a fault code.
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Injectors were tested by electro diesel and deemed not up to scratch. Hence the replacements

So,

Injectors now coded.

Both sensors on common rail replaced
Fuel pump replaced

Still the same outcome

Fuel is definitely getting to the top of injectors.

I'd say there definitely still not firing.


Codes reset.

009b comes back every time.

Tested for 12v on pins, this came back correct on the sensor on right of the common rail. Although I got the earth from the battery. I wonder if the 2 pins are gnd and 12v

Ohms did show when I went to ground then to one of the 2 pins.

Last edited by Jw2000uk on 4th Nov 2022 6:47 pm. Edited 2 times in total

I tested 4 sensors.

They all react on the diag kit, as high input when unplugged.

The fuel sensor on right. Doesn't throw a high input code when unplugged



Video of fuel pressure while cranking

&feature=share

The fuel pressure regulator is on the right of this picture, at the end of the fuel rail.
The rail pressure sensor is on the left of the rail in this picture.

If the pressure sensor (on the left) isn't connected, the engine shouldn't start, or if it does it'll run badly.

If the fuel pressure regulator isn't detected (not plugged in or has a damaged wire), then the ECM wouldn't be able control the rail pressure, so the engine won't start.

The pressure regulator requires power from the ECM to close its bypass port, or rail pressure will never build, as the fuel is simply passed to the bleed off pipe.

The pressure regulator on the pump is simply there to pass fuel back to the intake side of the pump under some conditions, and the engine will normally run quite happily without it connected at all.

So what readings are you getting at the pressure regulator (right of the rail in the picture), both on the regulator pins, and the plug contacts? Hyundai Ioniq 5 Ultimate. The family car.
2009 Rimini Red SE TD4. Gone.
2006 Tonga Green i6 HSE. Gone.
Audi A5 convertible, my daily driver.
1972 Hillman Avenger GT, the project.

Great info mate.

So, focusing on the regulator

I get 12v on the plug. Although I got gnd from the battery.
Is the 2 pin plug gnd+12v? Or is it signal+12v

This was the only test the snap on diagnostic suggested. The rest were under running conditions.

Sensor contacts I tested with ohms. And I cant remember the reading. But it read the same as the sensor I removed. So I'm assuming they both can't be knackered.

As said though, it's the only sensor that doesn't throw a high output code when unplugged. So there is definitely something up with the wiring I'd say.


Appreciate all your help so far..


This is what I believe is happening.. as you say.

"The pressure regulator requires power from the ECM to close its bypass port, or rail pressure will never build, as the fuel is simply passed to the bleed off pipe."

I think that this is a description of the Circuit ( O_T_PCV ) that is indicated as faulty. (From Repair Manual)

Pressure Control Valve (PCV)

The PCV is mounted in the end of the fuel rail (transmission end) and connected to the ECM via the engine harness. The
PCV is a solenoid-operated valve controlled by a 12V PWM signal. The ECM operates the PCV to adjust the fuel pressure
within the fuel rail. Relieved fuel is directed through the fuel rail leak-off pipe to the fuel filter return circuit. The leak-off
fuel also provides cooling and lubrication for the PCV.
For additional information, refer to: Electronic Engine Controls - 2.2L Diesel (303-14 Electronic Engine Controls - 2.2L
Diesel, Description and Operation).

The PCV is normally open when the solenoid is not energized by the ECM. The resistance value of the PCV solenoid coil is
3.6 ohms at 20°C (68°F).

The PCV is also used by the ECM to provide direct control of the fuel system, in the following situations:

During sudden transient phases in engine speed (suddenly lifting off the accelerator pedal, for example) where VCV
action is not sufficient to affect the supply of fuel to the fuel rail.

To control fuel pressure in the event that the VCV fails.

During the fuel heating period, when supply fuel temperature is less than 40°C (104°F). The VCV is fully opened by
the ECM and the HP pump compresses a maximum quantity of fuel to raise the fuel temperature. The PCV is then
modulated by the ECM to provide leak-off fuel from the fuel rail to the fuel filter return circuit. The fuel is then
recirculated through the fuel filter and back to the HP pump.

When the fuel supply temperature is greater than 70°C (158°F). The PCV is modulated by the ECM to release fuel
rail pressure, subsequently decreasing the fuel temperature to protect the fuel system components. Leak-off fuel
from the fuel rail is directed to the fuel filter return circuit and back to the fuel tank.

During engine shutdown to progressively collapse fuel rail pressure. FL2 XS SD4 Auto 2010 2012-2017 (21k - 91k miles) (MY2011)
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It sounds like there's a wiring issue, if the pressure regulator is giving a resistance of under 4 Ohms.

There is a known issue where the wiring harness under the air filter housing can get damaged because its not routed correctly, so it's worth looking at that.
There is another less common issue where water can get to the ECM plug, causing corrosion and connection problems. Hyundai Ioniq 5 Ultimate. The family car.
2009 Rimini Red SE TD4. Gone.
2006 Tonga Green i6 HSE. Gone.
Audi A5 convertible, my daily driver.
1972 Hillman Avenger GT, the project.

Thanks for the replies lads

Now I can focus purely on this. Hopefully I'll be able to trace a issue in the wiring to the regulator.

It's getting 12v on the plug.
Its a 2 pin. 12v+control.... so in reality, it's a break in the control wire.

I'll do more ohms testing.on the sensor.

But the fact there's no high input fault code when unplugged. Really does point to the wire.


I'll try and ohms test the control pin from plug to ecu or wherever it ends up



All stemmed from about 5 reduced engine faults. Managed to keep restarting to get home. Then no restart.

And the rest is history lol

Has the vehicle been diagnosed with JLR SDD? Or just a universal code reader?
SDD is able to run diagnostic routines which universal code readers can't do.
That's what I'd be doing first, but I do have SDD which helps. Hyundai Ioniq 5 Ultimate. The family car.
2009 Rimini Red SE TD4. Gone.
2006 Tonga Green i6 HSE. Gone.
Audi A5 convertible, my daily driver.
1972 Hillman Avenger GT, the project.

Only a snap on tool.

I can get a laptop and the sdd kit

Or I could give in, and take it to a auto electrician who has that kit

I'm 50/50

UPDATE.

Car was with a auto electrician for 2 months.

Although he found a break in the wiring. Apart from that it just sat there..so I've got it back.

So now the engine wiring harness is repaired, I've still got the p009b code

New ecu, repaired loom.


I've stripped the loom to get more of a understanding and check myself.


The code comes up still regardless if its plugged in or not. In different coded ecu's. Same code.

Question 1. The signal cable in the 2 pin plug, goes back to ECU. Should it have any volts with key in.

Question 2. Does this sensor go through a relay or a fuse atoll. As even though the ECU is throwing 12v to it.
The fact its open circuit and not a high input code, seems like the fault is before the ecu