Discuss Land Rover P1260 Fault Code Fix (FreeLander) Td4 BMW Installation in the Auto Electrician Forum area at ElectriciansForums.net

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My customer read on many forums about people suffering to solve a problem with the above Land Rover with regards to a fault code known as P1260. It seems many people have used trial and error methods to resolve the problem but as far as he could see nobody found a fix, or nobody had posted a fix.

My customer had this problem with his own Land Rover, same model as above and somebody he says advised him to contact me. I said I would investigate the problem and advise of the cause, if I found it.

I checked the type of system fitted to his Land Rover, which was the BMW installation known as the DDE version 4.0. This means the system is a Digital Diesel Electronic version 4.0 of the Common Rail Diesel Injection System type. NOTE, if you have never worked on these Common Rail Diesel systems, be warned that the fuel pressure in the high side of the system is up to 1800 bar, that is 26280 PSI, you will get seriously hurt or loose parts of your body if fuel under that pressure penetrates your skin when disconnecting sensors or pipes. DO NOT DISCONNECT ANY FLUID PIPES OR SENSORS ON THE HIGH SIDE OF THE SYSTEM UNTIL THE SYSTEM HAS BEEN DEPRESSURISED.

The Investigation

I connected a scanner to the 16 PIN diagnostic socket to read any stored codes, PO206 [Undocumented] was present, along with P1260, PO204 [injector cylinder 2], and P1E25, where the technical data had no information to advise what the code referred to.

I first looked up the meaning of the codes, which referred to the PO206, known as cylinder number 6. Because this engine is a four cylinder, that code can be ignored. The next code PO204 referred to cylinder number 2 injector misfiring, this can be caused by low fuel pressure and or an electrical fault. The next code was unknown and I had to complete some research to prove what the code was referring to on the Land Rover, I'll not go into depth with it now as it would take quite a long time to write it up, so a brief explanation of the code I will provide at this time.

P1E25 is the code I am referring to, hence;

P = Power train control,
E = Future Allocation,
1 = Fuel or Air,
25 = Malfunction area.

This code was the last fault area I looked at, the reason for this was because as far as reasonably possible if I could get the engine to run reasonably without it then I can unplug sensors until the code appears. This is how I proved the P1E25 referred to the camshaft position sensor, then all I had to do was research information to find what E125 was referring to as above.

The last code in the list was P1260, this code refers to delivery fuel pressure monitoring. A thorough look round the engine bay and the fuel components, pipes, hoses tank etc all seemed OK and nothing seemed to have been damaged.

Checking live data is very important but not the first check that should be carried out, hence the above checks visually. Live data showed that the fuel pressure was operating at 1.65 bar on the low pressure side, so a look at the technical data confirmed that the operating pressure was below the vehicle manufacturer recommendations of 2.6 bar [+ -] 0.2 bar, hence a problem had now been found.

As the technical data did not advise what the fuel volumetric flow rate should be, if not available from the manufacturer, then a good comparison from a new pump can be used, or a mathematical model could be worked out. I worked out that a new pump should be able to deliver 190 1/h, so if my pump was able to supply 3 1/min at the rated pressure then the pump should be OK, however the pump was found to have a low supply rate.

A new pump and filter were fitted and the engine ran on all four cylinders without misfiring, I thought I had fixed the problem, then after clearing the codes and running the engine at increased speed, the code P1260 returned and the engine went into limp home mode, the engine speed capped at about 3K rev's.

Further testing of the high fuel pressure side of the Common Rail System did not find any additional problems, where a high fuel pressure gauge was installed and the minimum rail pressure of 250 bar in 3 seconds was achieved, and additional fuel rail pressure testing using the Sykes hand held electronic test equipment proved that the fuel rail pressure via the fuel rail pressure sensor could achieve maximum rail pressure when loaded up, however, this test is very reliant on the fuel rail pressure sensor (FRP) working correctly, it is not however a direct reading of the fuel pressure like using a gauge.

Word of caution, these early Common Rail Fuel Systems do NOT dump the rail fuel pressure immediately when the ignition is switched off, the pressure is a gradual reduction and I found from experience using the test equipment that after standing 24 hours, the rail pressure was still at 3.50 Mpa, that is 35 bar. That's enough to take your fingers off if you tried to remove an injector pipe etc.

Now the fault code P1E25 identified as the Camshaft Position Sensor I am now able to test it using a scope, the technical data advised using settings of 20V and 20 ms. Although I am not able at this time to upload my scope reference patterns, I can advise that errors in technical data soon become apparent and we must be able to establish correct scope settings when things go wrong!

The camshaft position sensor settings were found from creating a mathematical model, as a guide the technician needs to have some experience in the area of mechanical engineering science or other options will be required.

The idle speed is automatically set at 780 [+ -] 50 RPM from live data, from experience the cam journal diameter is approximately 38 mm, thus I can't wait a minute to read a signal in electronics, its way too long a time period, so 780/60 equates to 13 RPM, multiplied by 0.0385 equates to a scope setting of 500 ms, now the camshaft position sensor can be read on the scope and looks OK.

Remember I still have the code P1260, looking around the engine bay I noticed a fuel type of sensor located in series with the low pressure fuel hose, along the chassis rail, this sensor had a 3 pin electrical connection, and referring to the wiring diagram I found that this sensor was called a fuel system pressure sensor, not to be confused with the fuel rail pressure sensor (FRP), which is a different sensor.

From the technical data I was advised that the voltage supply to this sensor, which by the way is a potentiometer type sensor, should be 5V at PIN 1, PIN 2 should be 0V, and PIN 3 at idle should be approximately 4.3V, and when the low fuel line pressure increases the voltage output should increase from 4.3V to just under 5V, in practice the voltage reduced to 1.7V, thus putting the DDE fuel management system into limp home mode logging code P1260.

A new fuel system pressure sensor was installed and the code cleared, a road test performed and live data recorded from the Land Rover for future reference. The fault code P1260 did not return and the Land Rover has now been confirmed as FIXED.

A couple of helpful notes.

When looking at live data, areas like the injectors will have readings presented in microseconds, and technical data will show injectors in milliseconds, some technicians could become confused, hence;

Pilot injection time in the technical data is normally advised in milliseconds [ms], but live data in microseconds [us]. Main injection time is the same, add the live data readings together, i.e. [us] and divide by 1000, this will show if the live data readings are similar to the technical data shown in ms.

The injectors voltages are approximately 18.35V each at idle, this is normal, but live data on the scanner will show two sets of readings, injector 1 (V) 73.7V @ idle and injector 2 (V) 26.3V at ALL engine speeds, this is normal. Injector 1 (V) should increase to about 79 Volt when the engine is accelerated and adding injector 1 and 2 voltages together should not exceed approximately 105 volts.

On my scope my notes taken suggest I used a mathematical model of around 0.868 ms with a 20V scope setting to test the injector patterns on the scope, which looked OK to me when compared to the technical data.

I hope this information may help others with both insight of system design and tracing faults safely on Common Rail Diesel Systems, but please ensure you follow the vehicle manufacturer recommendations at all times for health and safety reasons.
 
Thanks for taking the time to do that, and highlighting the dangers of the high pressure system.
Also the anomalies of the codes that mislead.
 
Hi dude,fair play to you,for dedication,but if problem solving is a hobby,you own the perfect vehicle ;)

Like a lot of systems of this type,fault codes do not always apply directly to a single component. On many occasions,it is error codes from components downstream of a faulty device,which give codes,as a result of upstream anomalies.

In the case of,say,a fuel rail pressure sensor,an OC or short,may give the ECU cause to fault code it,but if it is malfunctioning in reading incorrect pressure,the next components will just have to deal with that situation,which then gives rise to another set of symptoms,and codes.

If you add to the mix,ageing components,second and third faults,and any combination of intermittent occurrence... this is when a trade-in looks like a lifeboat :)
 
Hi dude,fair play to you,for dedication,but if problem solving is a hobby,you own the perfect vehicle ;)

Like a lot of systems of this type,fault codes do not always apply directly to a single component. On many occasions,it is error codes from components downstream of a faulty device,which give codes,as a result of upstream anomalies.

In the case of,say,a fuel rail pressure sensor,an OC or short,may give the ECU cause to fault code it,but if it is malfunctioning in reading incorrect pressure,the next components will just have to deal with that situation,which then gives rise to another set of symptoms,and codes.

If you add to the mix,ageing components,second and third faults,and any combination of intermittent occurrence... this is when a trade-in looks like a lifeboat :)

I agree totally with you above, there are many other areas that set this fault code P1260 also, other experiences I have had in the past are, ECM pins furring internally causing bad connections, HPP pressure control valve malfunction, poor connections, fuel pump fuse, partially blocked fuel filter but to name a few.
 

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