Q: Codes P0171 and P0442 - is it a gas cap issue?

asked by on October 17, 2016

Ran codes. Got code P0171 and P0442. I think the later could be a gas cap issue. The earlier appears to possible be several items, (Fuel Filter, MAS Mass Air Sensor, Idle Control Valve, ) I had CCVV and hoses replaced last Jan. 2016. at 100K. The light came on at around 107K.

My car has 109000 miles.
My car has an automatic transmission.

Check Engine Light is on Inspection $94.99 - $114.99 Get a Quote

Hello. These "small leak" codes can be very frustrating! Both of these codes (P0171 - lean condition, P0442 - small evaporation system leak) are the result of an air leak in the engine’s air intake system. Causes can be leaks in the many rubber hoses in the air intake, leaking hoses from the secondary air pump, a fuel tank vent valve not sealing, a gas cap that isn’t tight as you noted, and so on. I would recommend having your Check Engine Light inspected by a mobile, professional mechanic, such as one from YourMechanic, to diagnose the problem, get an accurate assessment of damage and cost estimate for repairs.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing


Experienced Mechanic?

Earn up to $70/hr

What others are asking

Truck stalls out when driving
Stalling issues can be not only dangerous but nerve racking, as they can be often hard to predict. There are many possible causes, and to help the technicians narrow down the cause, it is recommended to track the time, temperature...
What is automatic transmission adaptive learning?
While most cars with automatic transmissions offer basic operability, yours is different. The automatic transmission is equipped with a learning tool that allows it to learn how you drive and adapt to those needs. This offers better performance and helps...
Car overheating with new radiator
You might also have issues with your radiator cooling fan. It should spin most the time when you have your air conditioning turned on. You might also either have a clog in your system or internal engine issues. A qualified...
New battery drained for no reason
There is most likely an electrical component that has failed, causing the battery to drain. These can be very tricky to diagnose. Basically, you need to be able to measure how much current is being drawn from the battery when...
No brakes when starting
Hey there, there are several possibilities for this to occur on your 2008 Pontiac Solstice. In this case, it sounds like there could be moisture building up in the lines or a leak causing air to enter the hydraulic braking...
I can not hear fuel pumps kick on when I turn key on , I have checked relay, fuse and replaced fuel tank select switch.
Hi there. A plugged fuel filter (https://www.yourmechanic.com/services/fuel-filter-replacement) could cause the fuel pump to work harder and eventually fail. The filter plugged will not prevent the fuel pump from coming on. Turning the key to the on position only, the fuel...
My car is using lot of water and i don't know why.
Hi there. First check the oil in the engine. See if the oil is milky and not dark in color. If the oil is milky, then there is either a head gasket that is burned and putting the coolant into...
2009 Volkswagen Passat Aux Not Working?
Hello. To help you find the cause of your aux cord not working I suggest doing a little process of elimination. If you have another device try to plug that device and Aux cord into your car because it may...
Would performing a heater core bypass give my AC colder air in my 2001 Jeep Wrangler
Hello. Unfortunately this will not help. If the blend doors under the dash are working fine then the heater core should be completely blocked out when the a/c is on. If the system is functioning properly and the system pressures...

Related articles

Is It Safe to Drive With the Gas Cap Light On?
You have what sometimes seems like innumerable warning lights in your vehicle. Some of them alert you to very serious problems. Others,...
Symptoms of a Bad or Failing Fuel Filler Cap
Common signs include the cap not tightening properly, a fuel smell in the car, and the Check Engine Light coming on.
Symptoms of a Bad or Failing Gas Cap
Common signs include the cap not tightening properly, a fuel smell in the car, and the Check Engine Light coming on.