Engine Management Light Won’t Go Out

[Kay98989]

Hi Everyone. I need some advice please, here is a summary of my issue:

• February 2023 - Replaced the thermostat housing due to a leak
• July 2023 - attempted a DPF clean through a service - only 25% blocked
• August 2023 - 4 part carbon cleaning - engineer confirmed the issue is electrical and suggested an auto electrician because the thermostat and egr are potentially near each other
• Various scans have produced codes related to DPF (now resolved), EGR (still present) and crank case (still present)
• September 2023 - cleaned EGR fully manually, taking it apart
• September 2023 - replaced the EGR and thermostat, light wouldn’t go away. Since replacement the thermostat has been extremely slow to rise to temperature, takes about 2/3 miles.

Overall, there had been zero reduction in performance (i.e. it is not in limp mode)

• October 2023 - Mechanic used Wynn's Formula Gold High Performance Diesel System Treatment, started going into a ‘limp’ mode where Manual mode wasn’t available
• November 2023 - Used BG 245 system cleaner. Drove from Essex to Warwick (and back) - went into that same ‘limp’ mode

No mechanics seem to have any idea what’s going on, I’ve been to three different ones. I now suspect its the ECU that’s the issue but no idea.



Existing codes

• P059811 - the coolant thermostat has a short circuit to ground. There is a short circuit to ground (Active and stored)
• P059713 - the coolant thermostat has an electrical fault or open circuit. There is an open circuit (stored)
• P053A13 - the heating of crankcase ventilation system 1 has an electrical fault or open circuit. There is an open circuit (stored)
• P245A13 - the switchover valve for bypass ‘exhaust gas recirculation cooler’ has an electrical fault or an open circuit (active and stored)
• P053B11 - the heating of crankcase ventilation system 1 has a short circuit to ground. There is a short circuit to ground

I’d really love to hear what people think about this I’ve been ill advised up until now, really appreciate your advice.

 

[philnewmerc]

Someone far more knowledgeable than me will be along I'm sure, but in the meantime: what's the car and have all these mechanics been using STAR to read the codes? You need that.

 

[ALFAitalia]

Last time I worked on a car (Alfa Giulia Quad) with so many grounding and electrical faults (that was not a failing battery) it was the result of pretty severe rodent damage to the ECU wiring loom. The loom was over £400 for a used one....well into 4 figures for a new one that we could not get anyway. Getting at some of the loom was a pain too.....so we discussed it and I ended up spending about 3 hours, cutting, extending, soldering and heat shrinking the original loom in situ. About 2 years later all is still good!! Unlikely this is your case but worth a look and vey easily missed.

 

[Supernoodle]

You'd have to be bloody unlucky to have that many faults in the ECU

All the components mentioned in the faults, thermostat, heater, bypass etc all look like 12v components.
An ECU is the low side driver for such components, ie it switches the ground side.
Imagine the EGR cooler bypass is connected on one side to 12v, the other side to the ECU. At that ECU pin the voltage will be somewhere above ground potential and between 12v. The ECU will be happy. You remove that 12v to the bypass, that pin will be sitting at ground. ECU doesn't know why, so will report short to ground or open circuit.

I suggest you've got a problem with the power for those components, may be damage to the loom as mentioned.