I'm going out of town next week and had a "Engine System Service Required" message pop up in my dashboard today. Check engine light has been on but when I checked it last month it was the catalytic converter. I've also had my engine cooling fan replaced last year, as it stopped working. Plugs and coils seem to have been going out which I've been replacing as well. I believe this could be the fault of my coolant sensor going out, which I'm replacing tomorrow as well.

I checked the codes and they are as follows:

P2419 Evaporative emission system switching valve control circuit low

P240a Evaporative emission system leak detection pump heater control

P2401 Evaporative emission system leak detection pump control circuit

P420 catalytic converter

P0117 powertrain control module. (Could this be the temperature sensor?)

I need to know what other steps to take after I replace my coolant temperature sensor. I would appreciate any thoughts and feedback!

 

This video shows the leak detection pump that your codes are for. I would inspect the hoses if possible. They are not very easy to fully inspect. Check the connections on either ends etc. Possible need for replacement. P0117, the temp sensors are cheap and important for the car. Its what the ECU uses to adjust fuel during start up. Those sensors are often inexpensive and easy to replace. A cheap "shot in the dark" so to speak. I had a car with starting issues in the cold, ended up being the coolant temp sensor on the thermostat.

Those pumps with hoses go for about $220 for genuine volvo.

 

You have been driving with the check engine light on and now you are going out of town and are concerned? The po117 code could be a problem. If you have the 6cyl broken thermostats are a common problem and could be causing that code (as well as other bad things if driven too long) So I would be checking that system closely to avoid potential serious problems. 5 cyl thermostats are not as problematic but still do fail. Does your scan tool offer live data? What temp does the engine warm up to? (temp sensors are an old very reliable technology and rarely have problems, so if I were guessing, i would guess somewhere else)

For the rest of the codes - Just keep driving the car. None of those codes will change the way the car runs. You probably have a bad leak detection pump (a common failure) - which won't change the way the car runs or have any thing to do with reliability.

Then when you have time, follow a rational, reasonable diagnostic procedure to determine what might be causing those codes to appear. That procedure is not "guess, buy, replace and hope it's fixed". That can get very expensive. The easily found free copy of VIDA 2014 has explanations and rational suggestions of possible causes with detailed test procedures.