Fault codes

[KennyW]

Hi All,

Trying fathom out a new problem.

Last summer replaced dpf after these fault codes appeared while in France.
P1496, P1497 P149C and finally P0234.

Cleared these faults after fitment and informed ECU of new DPF no problems until recently when P0234 reappeared.

Just done diagbox global test and found this new fault P1396.

It looks like faulty solenoid, vacuum hoses or worse still EGR valve or turbo.

What could it be any thoughts gratefully received.

Kenny

[GiveMeABreak]

Hi Kenny, a few pointers for you:

Fault P0234 is a boost pressure regulation fault, meaning the air pressure is above the reference value.

Description: The engine speed is 2000 - 3000 RPM with the engine torque below 300 Nm and secondly, the measured turbocharged air pressure is 450 mbar above the reference value for 6 seconds.

For the fault to trigger, the engine speed needs to be above 1500 RPM and the actual engine torque higher than 100 Nm.

The fault can disappear on its own if the car is driven for 5 minutes with the engine hot with several accelerations under full load for 10 seconds, with foot off in between.

Whilst this fault is active, the following downgrade operations are enacted:

• Deactivation of the pilot and post-injection injections
• Deactivation of the request for regeneration of the particle filter from the diagnostic tool
• Deactivation of the EGR function
• Cutting of the exhaust heat saver function
• Prohibition of regenerations of the particle emission filter and stopping of those in progress
• Deactivation of the kick-down for automatic gearboxes
• Limitation of performance
• Request for emergency closing of the turbocharged air cooler by-pass
• Deactivation of the tight spot for the cruise control

The engine warning light will also be lit.

Symptoms noticed: Noise, Diesel fuel consumption a bit higher, Lack of power, Engine hesitating, cutting out, Smoke from the exhaust.

Suspect Areas: Manifold air entry pressure sensor, Turbo air cooler by-pass unit, Electrovalve of the turbo air cooler by-pass unit, Position indicator of the turbocharging air cooler bypass unit, Turbocharger, Turbocharger solenoid valve, Position indicator of the turbocharger.

So if you suspect the MAP sensor is faulty, it could be sending the wrong values and having a knock-on effect down the line. It is part 1920QR.

The MAP sensors on these measure both the Air temperature and the air pressure.

[KennyW]

Thanks Marc,

Never thought of the MAF sensor

Kenny

[GiveMeABreak]

Not the MAF kenny, the MAP

Also called the Inlet Air Temperature and Pressure Sensor.

This sensor measures both the air temperature and air pressure and is first on the suspect list in my previous post. It is part 1920QR.

[Paul-R]

Are you sure about the temperature Marc? I thought that was co-located inside the MAF.

[GiveMeABreak]

Yes, I'm sure Paul - this sensor is for the manifold specifically.

"b" Resistive Plate. "c" Resistor for measuring the air temperature. "d" Diaphragm.

The incoming air is diverted into 2 sections - one channel goes up and forces the diaphragm up against a resistive plate, which is then converted into an electrical current.

For the air coming through the other channel at 'c' an NPC (Negative Temperature Coefficient) sensor is used to change the resistance in line with the air temperature.

This sensor is specifically for measuring the air and temperature around the manifold.

The MAF also has a temperature sensor Paul, so you are correct there, but they are for different parts of the system.

Here are the components in a representative diagram. I've emboldened the 2 sensors in the table.

Reference Designation "A" Turbocharger Blades Control Diaphragm (With Position Copy Sensor) (1) Engine ECU (2) Variable Geometry Turbocharger (3) Proportional Electrovalve Controlling the Variable Resistance Turbocharger (4) Air Flowmeter by Mass (5) Air Filter Unit (6) Turbocharger Air Cooler (7) Double Air Mixer With Position Repeat Sensors (8) Inlet Air Pressure and Temperature Sensor (9) Turbo Air Cooler By-Pass Control Electrovalve (10) Air Metering Unit Control Electrovalve

[KennyW]

Okay, Thanks Marc fortunately I found the part via the part number so got the right part.

Ignore my senior moment, I was reading an old post about MAP's & MAF's and a comprehensive reply from Jim (Citrojim).

Kenny

[GiveMeABreak]

No worries - I thought so Kenny.

The MAP, by its nature of having a diaphragm is likely to be a failure area at some point I suspect.

[KennyW]

Marc,

Can you confirm the position of the Map sensor ? Is it located at the rear of the engine besides the electro vlave solenoids ?

Kenny

[GiveMeABreak]

It should be near the manifold air intake, item (7)

[KennyW]

Thanks Marc.

[rafal85]

Hi.
Have you fixed that?
I have similar issues