Q: Rough idle with DTC P0171, engine stalls unless MAF sensor is unplugged - 2007 Volvo S40 2.4i

asked by on

I am having a problem with the air or fuel system in my car. Check engine light is on with error code 0171. Car seems to run okay when started from cold. After engine is warm, if I turn the car off then start it again, it idles very rough and often stalls.

I removed the MAF sensor and cleaned it with CRC MAF Cleaner, but the same behavior continues. If I unplug the MAF sensor completely, the car seems to start fine. With the MAF plugged in, though, the car will not start or will start, idle rough, and stall.

Is it safe to assume the MAF sensor needs to be replaced or is there something else that could be causing this issue?

My car has 162000 miles.
My car has an automatic transmission.

Your mass air sensor has most likely gone bad and/or is not giving correct data to the computer. Replace the sensor, clear the codes, and retest this.

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. Rough idle with DTC P0171, engine stalls unless MAF sensor is unplugged - 2007 Volvo S40 2.4i

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: Q: Jerking reaction when accelerating

This may be related to a faulty throttle position sensor or potentially a dirty or failing mass air flow sensor. The mass air flow sensor is a unit in the intake system that monitors air intake as it is mixed...

Q: Q: Key locked in ignition.

Try a different key first. If the other key also does the same thing then try to move the steering wheel to the left and right to make sure it is not in a bind. If that does not work...

Q: engine misfire on running temperature

This sounds like you may have potentially two unrelated problems. The first may be related to the issue of timing causing the misfiring, and the second could be related to the fan running more than usual. First, the misfiring...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.