New to site. First Volvo. 1998 Volvo S70, 137,000.
Got code P0455. Read here that that could be bad vacuum hoses. Could bad vacuum hoses be causing the other code I'm getting, P0172, which is saying "Bank 1 system too rich?" Any thoughts would be appreciated. Thanks in advance! The info here is great!!

 

Do u have the turbo model or not? Makes a big difference. I repaired a massive intercooler leak that was causing multiple codes. in the same exact car but it was turbo.

U generally get lean codes from vacumm leaks tho, and an intercooler or turbo piping leak would definitely cause lean codes as well.

There is a chance that your coolant temp sensor is bad. If u have rich codes it generally is but does the car have more issues like hard start at temp, or cooling fan always running? These are tall tell signs u need a CTS. It tells the computer a lot. If u have di-electric grease u can slather it in the connector pin, if it doesn't help then the sensor is bad.

It's located right next to the thermostat. It screws into the thermostat housing, which is off the head and goes to the top radiator hose.

Check this for sure, it fixes a lot of issues if it is malfunctioning.

If it's bad the computer goes into failsafe mode in which the circuit tells the computer it -40 degrees outside so the com. Thinks ur intake air is super dense and it makes up for it by dumping ungodly amounts of fuel.

This will also cause damage to catalytic converter if it continues to run rich.

 

Take a piece of 3/4" vacuum line and (with engine running) listen around the hoses in the engine bay. The vacuum hose to your ear will work like a stethoscope and may help you find a significant leak.
Needless to say, keep it and yourself away from belts and fan, etc.

 

I don't like the idea of "spraying" volatile liquids around in the engine bay to find leaks...but that's just me...

 

Thanks! No, not a turbo. I replaced the thermostat 2 weeks ago, CEL went off for about 30 miles then came back on. Replaced it when the fan kept running, that solved that problem. No starting issues. Seems to be running well except for the CEL being on. Need to get it through emissions inspection to renew plates. So have to track down the problem. Should I go ahead and just change the all the vacuum hoses out? I know they have never been replaced. Gas cap is new and sealing. Appreciate the help!