The electric PTC heater has been an issue since owning MY2016 PHEV.  When I test drove this vehicle on a sunny day in May I wanted to make sure the heating worked.  Having come from a Nissan Leaf I got used to Pre-heating the car in winter. The PHEV has this facility.

On the test drive using only electric motor I did not have heat as quickly as I hoped. In a strange car you are in an anxious state trying to master the controls and not crash.  After a while the heat kicked in and I assumed I did not have the heating controls set right. But what I eventually learnt was that the Outlander will bring the engine on with high performance demand.  I did not know this or how to monitor for it.

It is also the case that the engine will drive the heating if the temperature is less than 10c.  If you use the dashboard energy info screen you can see the vehicle demanding heat from the PTC heater, but that goes around to 5Kw whether it is working or not!

When I tried the preheating at home it was very poor. A telling symptom was when it is plugged in to charge, the preheat only pulls 1.4Kw. Normal charging starts at 2.4Kw.

Warranty

The vehicle came with 3 months cover so I pursued that but the company I purchased the vehicle from were on the fringe of ceasing trading and are now no more.

Seeking a Remedy

I had read on the forums that Mitsubishi offered a service to flush the coolant system with an acid to remove sludge, and also the PTC heater can become blocked with crystalized anti-freeze.  I paid for this at £640 it made no difference.

Garage Repair

I took it to two garages for a quote to fix the issue and both were over £1500 because a new PTC heater is over £900 and it is labour intensive.  I could not find a garage that would fit a second-hand unit and anyway they are still over £500, used!

On the Bench

I bench tested my unit and it could barely raise non-flowing coolant to 35c consuming 0.45 amps. So with coolant pumping through it will never get warm enough.

I realized that my vehicle had a 2nd Generation PTC heater that had been superseded with 3rd generation model. What is odd, is that these used retail around £120. So I wondered how different can it be?

Well, it is very different. Mitsubishi have obviously realized they created a dud with 2nd Gen PTC and revamped 3rd Gen into a smaller unit, with 4 elements not 3 and controlled by CAN instead. The outlet pipes are for 20mm hose where Gen 2 was 18mm.  So a straight swap was out of the question.

I wondered, could I used the old Gen 2 PTC circuit board inside the used Gen 3 heater?

Gen 3 on the Bench

On 240v with one element connected it raced up to 6 amps (1.4Kw) then slowly falls to 3 amps (720 watts).  The coolant filled unit reached 50c in a few minutes not pumped.  This clearly showed my old unit was f&*%*ed.

I set about fitting

Post Short Circuit

Car would not READY mode. an OBD2 scan revealed:

• Antilock Brake System – DTC error code P0557 Pressure Sensor Circuit Low Input.
• Air conditioning – PTC heater error codes B1114 & B1112 Overheat of inlet and outlet coolant.

This was missed by The AA breakdown service.  When I cleared P0557 DTC the “EV system service required” message on the dash was replaced by “Press the brake pedal to start”.