Skip the auto shop - Our mechanics make house calls

Q: Check Engine Light with P0174 code

asked by on

Check engine light came on last week. Car was running ok, but it needed to be checked. Had code pulled and it was P0174. I changed the PCV and cleaned the MAF with MAF cleaner. The next day after, the car had rough idle start and very sluggish acceleration. The symptoms do improve after the car warms up. Mpg is noticeably worse

My car has 198000 miles.
My car has a manual transmission.

As you know, this code relates to a lean fuel condition which can be caused by many different things, some of which you have already addressed. The oxygen sensors, which are part of your emissions system, read exhaust gases to determine whether or not the appropriate amount of oxygen is present in the exhaust. Based upon this reading, this information is relayed to the car’s ECU which then makes a determination as to whether or not to add more or less fuel to the engine. When too much or too little oxygen is present, this will cause check engine light to come on.

Too much oxygen may be present in the exhaust gas due to things like an exhaust leak, a vacuum leak, a faulty mass air flow sensor (causing a lean fuel condition) or faulty fuel injectors.

Too little oxygen may be present in the exhaust gas may be caused by things like a clogged air filter, a failing mass air flow sensor (causing too much fuel to be introduced to the motor), bad fuel injectors, or a clogged catalytic converter.

When the O2 sensor is not working properly, this will cause false readings to be relayed to the computer causing inaccurate adjustments to be made to the intake and fuel system in your engine. I would suggest having an expert from YourMechanic come to your home to diagnose the cause of the Check Engine Light in person so this gets repaired correctly.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
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. Check Engine Light with P0174 code

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: 2001 bmw 325xi P0174 and P0171 code,just had a tune up and one coil replaced car is stalling down,vibration and idle down when pre

The two codes that you have provided suggest these possibilities, at minimum, which possibilities may exist alone or in combination: an air leak after the mass air flow (MAF) sensor, such as a torn intake boot, or bad intake manifold...

Q: My 96 explorer starts then dies after a short while why

The starter does not have anything with the way the engine runs. The engine would need to be checked to see if it is loosing fuel pressure or ignition spark. You may have an ignition switch that is losing power...

Q: Vehicle stalled while driving

There are countless potential causes for your problem. The first step is to retrieve the diagnostic trouble code (DTC) associated with your check engine light. This code provides a starting point for the diagnostic procedure. Regardless, any testing will have...

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...