Q: P0171 & P0174

asked by on

Shortly after an oil change, I got the following codes - P0174 & P0171. I am assuming it is a fuel system pressure issue. Are there any simple checks or fixes I can perform before taking it to a mechanic - hoping to save some money.

My car has 98000 miles.
My car has an automatic transmission.

These two trouble codes are both related to the oxygen sensors located after the catalytic converter detecting that your vehicle is running lean. There could be a fuel pressure problem, vacuum leak, a vacuum hose left unplugged, an intake air tube not fully seated/loose, or any number of other possible causes. You may be able to do a visual inspection to see if any hoses were left off, or maybe a sensor left unplugged. If this happened within a day or two of the oil change, I would take it back to them and explain the situation. If nothing else, I would expect them to at least offer to do a visual inspection to be sure it wasn’t something they missed. If you’re still in need of help, YourMechanic offers a repair and diagnosis service preformed by a certified mechanic that will commute to your location to look further into these trouble codes.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. P0171 & P0174

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

Get a quote

What others are asking

Q: High-pitched sounds and shuddering at the stop light, dash lights on

The problem is in the traction control system, which detected a fault and turned on the VSC and check engine light. You will need to have the system tested to see what codes were stored and then have them diagnosed...

Q: BCI and FCW on my Infiniti JX35 turning off as soon I start the car and the car barely moves. Have to restart again to proceed.

There are software updates, and at least one specific Technical Service Bulletin, pertaining to the vehicle safety systems you note. All updates (re-programming) should be installed before, or during, any diagnostics because such may have an impact. There may also...

Q: What does the push button warning mean?

If your car has a continuously variable transmission (CVT) and a push button start, you may see the push warning show up on your vehicle information display. The image display shows the word “Push” and the outline of the start...

Related articles

How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...