Transit Engine Management Warning Light stays on

[waste bin]

I have a problem with my 2000 (according to V5) Mk5 (smiley) Ford Transit 2.5 turbo diesel motorhome. On a LCY190 chassis, done 70,000 miles, owned by me for 19 years.
The red Engine Management System warning light comes on and stays on, then it won't start.
The problem did arise after the water pump went. It was recovered to a garage and the timing belt and other belts were renewed at the same time!
That was two years ago and I can't get to the bottom of my problem.
It starts OK but after a while the red Engine Management System warning light comes on.
I eventually noticed that it comes on when the engine revs drop down, such as when pulling up at a road end or traffic lights - but only after a few miles. So it doesn't happen at my road end just seconds from leaving home. But it will after 5 or 10 miles when I slow/stop and the revs drop again.
It then stays on until my journey end.
Then if I try to start it after a couple of minutes, it's as though the battery is flat. Slow to turn over and won't start.
But after 10-15 minutes and I try it, it is lively and will start with no problem. And the red light stays out - until revs drop again as before.
If I keep blipping the throttle at junctions etc and keep the revs above 1000 it remains off.
I recently did a 30 mile trip. At home it started fine. The red light came on at a roundabout, about 10 miles from home, and stayed on. After 30 miles I stopped to collect something. I got back in to start it after about 5 minutes, and it would hardly turn over - felt like the battery was flat. I left it for 10 minutes and tried again and it was as lively as ever and started straight away. The red light then stayed off again until the revs dropped at a junction after a few miles.
I have put a new 'vehicle' battery in and a new 'leisure' battery in because they were getting weak.
I went to an auto electrician who said it could be the alternator (something to do with the stator). So I've put a new alternator on as well.
No change !
It appears to be charging all right. It always starts. Even after standing a while - just not after the red light has been on.
Any ideas would be greatly appreciated.

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For full context, visit https://www.motorsforum.com/ford_trucks/transit-engine-management-warning-light-stays-on-3333335-.htm

[Motors Advisor]

The problem you are experiencing with your Ford Transit engine management warning light staying on and causing difficulty starting the vehicle after the light has been on, could be caused by a variety of issues. Below are some steps you can take to troubleshoot the problem. If you have already done some of those, please post more information, and that may help with a better answer.

1. Check the codes: The first step would be to check the vehicle's diagnostic codes using a OBD-II scanner. This will give you an idea of what the issue may be.
2. Check the sensors: Make sure that all of the engine sensors, such as the crankshaft position sensor, camshaft position sensor, and mass airflow sensor, are working properly. These sensors can cause the engine management light to come on if they are not working correctly.
3. Check the wiring: Check the wiring to the sensors and make sure there are no loose connections or damaged wires.
4. Check the vacuum lines: Make sure that all of the vacuum lines are properly connected and not leaking. A vacuum leak can cause the engine to run poorly and trigger the engine management light.
5. Check the Throttle position sensor : The TPS sensor can play a crucial role in how your engine runs. A faulty TPS can cause poor running, misfires and can also cause the engine management light to come on.
6. Check the Fuel pressure: A weak fuel pump or a clogged fuel filter can cause the engine to run poorly and trigger the engine management light.
7. Check the Timing: Make sure that the timing belt is properly installed and that the timing is correct. If the timing is off, it can cause the engine to run poorly and trigger the engine management light.

It's possible that the problem lies in one of these areas, or it could be a combination of issues. If you are unable to resolve the problem yourself, it may be best to take the vehicle to a qualified mechanic for further diagnosis.

[Motors Advisor]

> Ford Transit 2.5 turbo diesel

OBD-II codes, or diagnostic trouble codes (DTCs), are codes that are stored by the vehicle's engine control module (ECM) when it detects a problem. When the engine management light comes on, the ECM will store a code that corresponds to the specific issue.

Here are some common OBD-II codes that may be relevant to your particular situation with the Ford Transit 2.5 turbo diesel engine:

+ P0401 - Exhaust Gas Recirculation (EGR) System Flow Malfunction: This code indicates that the EGR valve is not functioning properly, and that the EGR system flow is not within the expected range. This can cause the engine to run poorly and trigger the engine management light.
+ P0402 - Excessive Exhaust Gas Recirculation (EGR) Flow: This code indicates that the EGR valve is allowing too much exhaust gas to flow into the intake manifold. This can cause the engine to run poorly and trigger the engine management light.
+ P0603 - Control Module Long Term Memory Reset: This code indicates that the engine control module (ECM) has lost power or has been reset. This can cause the engine to stall or not start, or can trigger the engine management light.
+ P0622 - Generator Field/Fan Control Circuit Malfunction: This code indicates that there is a problem with the generator's field control circuit. This can cause the battery to die and the engine to stall.
+ P1335 - Crankshaft Position Sensor Circuit Malfunction: This code indicates that there is a problem with the crankshaft position sensor circuit. This can cause the engine to stall or not start, or can trigger the engine management light.
+ P1336 - Camshaft Position Sensor Circuit Malfunction: This code indicates that there is a problem with the camshaft position sensor circuit. This can cause the engine to stall or not start, or can trigger the engine management light.
+ P2263 - Turbocharger/Supercharger Boost System Performance: This code indicates that there is a problem with the turbocharger's boost system. This can cause the engine to run poorly and trigger the engine management light.
+ P2614 - Throttle Actuator Control Motor Circuit Malfunction: This code indicates that there is a problem with the throttle actuator control motor circuit. This can cause the engine to run poorly and trigger the engine management light.

It's worth noting that these are just a few examples of codes that may be relevant to your particular situation, there are many other codes that may be stored by the ECM depending on the issue. It is important to use an OBD-II scanner to retrieve the codes and diagnose the problem. Once you have the codes, you can use a code reader or search online to find the specific meaning and troubleshooting steps related to the code.

[waste bin]

Thanks for your advice.
It is currently at the garage having an MOT and doing some investigations into this. But no problem found yet.
One thing that mechanics say is how sweet it sounds when running. And there is no problem at all with misfiring or rough running. And starts easily except after this issue!
The timing and earths has been checked and are all good.
When timing is mentioned this could be to do with the timing belt (which is new and tested to be correct). But is there a timing option on the fuel pump?
I'll check to see what codes the garage have found, if any. And hopefully cleared - so anything still happening should show.
I'll report back when I've collected it.

[Motors Advisor]

> It is currently at the garage having an MOT and doing some investigations into this. But no problem found yet. One thing that mechanics say is how sweet it sounds when running. And there is no problem at all with misfiring or rough running. And starts easily except after this issue! The timing and earths has been checked and are all good. When timing is mentioned this could be to do with the timing belt (which is new and tested to be correct). But is there a timing option on the fuel pump? I'll check to see what codes the garage have found, if any. And hopefully cleared - so anything still happening should show. I'll report back when I've collected it.

It is good that the vehicle is at the garage for an MOT, as the mechanics will be able to run diagnostic tests to identify any trouble codes and pinpoint the cause of the problem. It's good that the engine is running smoothly with no misfiring or rough running, which is a positive sign.

It is also good to know that the timing and earths have been checked and are all good. The timing belt has been replaced and tested to be correct.

Regarding the fuel pump, it is not related to the timing but it is related to the pressure of the fuel system. If the fuel pump is not providing enough pressure, it could cause the engine to stall or not start. So it's worth checking the fuel pressure as well.

As previously mentioned, it's a good idea to check for any diagnostic trouble codes that may have been stored in the engine control module. These codes can help pinpoint the cause of the problem. If the garage is unable to find the cause of the problem, it might be worth taking the vehicle to a specialist in Ford Transit vehicles for further diagnosis and repair.

If you have any additional info, do post it here. Good luck!

[waste bin]

I now have it back. No faults could be found after much searching and testing at the garage, but I still have the problem.
I took it for a test drive for the garage and the engine management light came on when the revs dropped at a junction after 4 miles. Went back to the garage to turn it off and demonstrate bad re-start. It didn't show the problem, but started fine.
So I brought it home (another 5 miles) with the red light still on. Got home, turned off. Tried to re-start, but it wouldn't. Sluggish turning over.
Left it for five minutes and tried again. Started fine.
It appears to be 'hot engine' related.
Why would it be sluggish to turn over when hot and OK when cold?
If it was a sensor 'breaking down' when hot why should it make it sluggish to turn over?
Error codes found were
P1191 Key Line Voltage
P1197 Key Off Voltage Low
P1178 Boltup Limits Fault
The 1178 is 'Pump Bolt-up Limits' - something to do with "The fault indicates that the bolt-up angle has exceeded a high or low threshold. The bolt-up angle is the difference between the positions of the pump and engine position sensors."
My garage said that they were unable to clear these codes - need to go to main agent? So they could have been there for some time.
I've got myself a booster starter that I want to test to see if it will start it when hot. Might give some clue?