The thermostat seems to be OK: the engine warms up in a reasonable time and temparature gauge stays at 3:00 position.
In other treads of this forum about the same problem (PO128)somebody referred to the Volvo campagn 109.
Do you know anything about it?

Last winter 2003/2004 I had CEL coming up three times within 2 month:
1)CEL came on along with the Arrow (lower gear switch). The dealer has read the codes AT 313, ECM 76, ABS 313, 314 and traced it down to internale faalt in the Gear Postion sensor. Replaced the PNP switch
2) In month, CEL came up again. The dealer read it as C ECM 0D, A1 and traced it to a permanent fault of EBP (engine boost pressure) sensor ( i have turbo).
They replaced the sensor and warned me if ECM A1 returns, I'd need to check on ECT sensor and thermostat and may need to replace both.
3) Shortly after, CEL came back on. That time I did not take the car to the dealer, rather followed my friend advice and filled the tank up with the higher grade gasoline. After a couple of trips on the highway the light went off, and did not come back till now. My friend told me that the higher octane fuel can help to clean the sensors etc in the emission system.
I tried the same this time, and have not gotten any effect so far. The SEL stays ON. My friend also told me that if the higher octane fueld does not do the work, then I may try the fuel additive that helps to clean the system.

Thank you.