I had a referral for a mechanic to replace the thermostat on my Mazda3, 2005 2.0 Litre because the CEL went on and it threw the code P0126. The thermostat was indeed flaky and spent more time open then closed.
Upon checking the operating temps with an OBD scanner, coolant temps often would rise up to 200+F (93.3 C) but rarely when idling in traffic; however, most of the time it would be around 167F (75C). The replacement of the thermostat fixed that and now the engine is around 195 F (90 C). At idle it went up to 217F (103C) , but it's still within the "normal" range in the console (dash). With highway driving the air is cooling the engine but once again, no fan turns on. Temps do drop to around 195 (90C) but shoot up when idling or at a stop.
The person who did the thermostat replacement said the coolant fan should've kicked in after the car warmed up. He checked the connections, everything seemed as they should, same as the fusebox. I don't ever recall the fan ever turning on. I do hear the compressor turn on though, but not the fan. For example, after a long drive in the summer, I never heard the engine fan on after parking it. I also read somewhere that the coolant fan won't turn on until 220 F (144 C) but my mechanic says it should've come on around before 195F (90C).
Is there a troubleshooting procedure one can go through to determine what is the cause: The coolant fan wiring? Faulty coolant sensor, etc?
Upon checking the operating temps with an OBD scanner, coolant temps often would rise up to 200+F (93.3 C) but rarely when idling in traffic; however, most of the time it would be around 167F (75C). The replacement of the thermostat fixed that and now the engine is around 195 F (90 C). At idle it went up to 217F (103C) , but it's still within the "normal" range in the console (dash). With highway driving the air is cooling the engine but once again, no fan turns on. Temps do drop to around 195 (90C) but shoot up when idling or at a stop.
The person who did the thermostat replacement said the coolant fan should've kicked in after the car warmed up. He checked the connections, everything seemed as they should, same as the fusebox. I don't ever recall the fan ever turning on. I do hear the compressor turn on though, but not the fan. For example, after a long drive in the summer, I never heard the engine fan on after parking it. I also read somewhere that the coolant fan won't turn on until 220 F (144 C) but my mechanic says it should've come on around before 195F (90C).
Is there a troubleshooting procedure one can go through to determine what is the cause: The coolant fan wiring? Faulty coolant sensor, etc?
