Owners want to be able to change oil by themselves obviously.
On closed-type DPF models (all except MY 2008/2009 Legacy/Outback which are mated with open-type DPF) you’ll need to reset oil dilution parameter as it is calculated (not measured!) by the ECU. Basically active DPF regenerations in particular cause diesel fuel bypass into engine oil. Piston rings cannot seal perfectly.
No auto-detection! Since Subaru diesels, unlike Mazda for example, are not equipped with an oil pressure sensor, its software cannot detect an oil change nor deteriorated engine oil. Subaru’s simple on/off oil pressure switch (near oil filter) is connected to the dashboard. There’s also a low/high oil level switch available on Euro 5/6 models which won’t help here, too, although this one is evaluated by complex ECU algorithm.
Following info as seen in all managed-DPF-ROMs so far.
DTC P1468 Oil dilution (MIL remains off) is being triggered when oil dilution ratio ≥ 10 %. Results in DPF light flashing , there is no warning in advance! If oil dilution gets below 10 % (estimated evaporation) the light will also turn off.
The engine management software assumes 6.13 kg oil mass and this maintenance operation resets RAM variable “Oil Dilution Amount [kg]” to zero.
The ROM’s internal calculation steps are:
- update OilDilutionAmount [kg] according to CoolantTemp, Injection Quantities etc.
- OilDilutionRatio [%] = 100 * OilDilutionAmount [kg] / 6.13 [kg]
- EstimatedDistanceToOilChange [km], via LUT
Oil Dilution Reset
We’ve traced related Euro 4/5/6 ECU-ROM machine code. Here are all possible options:
Euro 4 (IV)
- Diagnostic protocol (SSM2 via Serial only). See post Oil Dilution Reset (K-Line, Euro4). There is no alternative method on Euro 4 models! (In theory, we could patch Euro 4 ROMs adding the same Euro 5/6 manual procedure as below. Not a trivial task, though, talk about hours of development and testing…)
Euro 5 (V), Euro 6 (VI)
- Diagnostic protocol (Extended OBD-II only since advanced stuff is not implemented in SSM2 anymore unlike Euro 4)
- Manual procedure, should be printed in the owner’s manual. The following table is derived from actual ECU software, confirmed in Euro 5 gen2/gen3 and Euro 6 ROMs:
Step Description Prerequisites
- Whole procedure must be done while parking.
- Engine must be running.
- Parking brake recommended, vehicle speed must be zero all the time.
1 Depress and keep holding brake pedal. (Slight pressure is sufficient). 2 (Rear) defogger ON 3 Lights ON (stage 1 = parking/clearance/DRL lights is sufficient)
From here you only have 4 seconds to accomplish each of the following steps and roughly half a minute total countdown!
4 Defogger OFF 5 Lights OFF 6 Defogger ON (again) 7 Lights ON (again) 8 Defogger OFF 9 Lights OFF 10 Release brake pedal.
Now the glow light (depicting yellow coil) will flash for 5 seconds indicating full success.
Otherwise wait for half a minute at least, then try again, repeating the whole procedure.
Many users have confirmed this procedure, e.g. Subaru Forester Owners Forum – Oil change on Diesel engine and ECU service reset.
Wanted – please contribute:
- dashboard video to confirm glow light flashing modes
- picture of car owner’s manual page describing reset procedure
Mazda SkyActiv-D 2.2 (CX-5)
“Engine Oil Data Reset”, either via OBD or manual procedure (test terminal & accelerator pedal).
ECU software contains algorithms that can detect deteriorated engine oil via oil pressure sensor, there are several DTCs.