odd engine light

SirBrickWagon · Post by **SirBrickWagon** » 18 May 2022, 12:20

so i'm faced with an odd situation here. my check engine light is on despite my code reader saying "0 DTC". it shows a medium severity and flashes some small symbols but no defined code. could it be that my exhaust is messed up? there might be a leak before or after the cat, or both. or might this just be that this is another "literally nothing is wrong" scenario?

Post by **misha** » 18 May 2022, 13:06

Do you have automatic transmission or manual?

If it's auto...there might be a TCM request to ECU to turn on CEL.

TCM codes can't be read with universal code readers....at least VOL-FCR is needed.

If it's manual....there is possibility that ECU have stored a specific DTC which can't be read with universal code reader in Pxxxx format...and again....VOL-FCR is needed.

SirBrickWagon · Post by **SirBrickWagon** » 18 May 2022, 13:46

misha wrote: ↑18 May 2022, 13:06 Do you have automatic transmission or manual?

If it's auto...there might be a TCM request to ECU to turn on CEL.

TCM codes can't be read with universal code readers....at least VOL-FCR is needed.

If it's manual....there is possibility that ECU have stored a specific DTC which can't be read with universal code reader in Pxxxx format...and again....VOL-FCR is needed.

it's an auto, could be anything. goes away after a few minutes of driving/idle

Post by **misha** » 18 May 2022, 14:26

You will need specific volvo scan tool to read specific codes.

Dealership,Vol-Fcr if it is M4.4...or 850 OBDII app.

Post by **jreed** » 19 May 2022, 05:35

Agreed with Misha's advice above. It sounds like you need to try a different code reading tool.