Skip the auto shop - Our mechanics make house calls

Q: Car failed emissions test

asked by on

My car failed an emissions test.

A: Your truck can fail an emissions test for a...

Your truck can fail an emissions test for a number of reasons. If I knew the results of the inspection I could give you some common causes of this failure. If the vehicle failed the visual check then there may be a part that is missing or not functioning as designed. If it failed the HC test then it may have a misfire or a failing catalytic converter. If it failed the NOX test then the EGR system may have a problem. A mechanic would need to know the results of the test in order to know where to start the diagnostic process.

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

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Save up to 30%

Get a quote

What others are asking

Q: Intermittent stalling while idle or driving

Hello there. Many common faults can cause your 1994 C1500 to have intermittent stalling when driving. You have done well in replacing the injectors, fuel pump, and other sensors as well as the plugs and wires, as these are typical...

Q: Idles and stalls again.

Hi There, It sounds like you may have a dirty or failing idle air control valve causing your engine idle to fluctuate and eventually stall. The idle air control valve is a small valve on the engine's intake system that...

Q: P0420 code and dash lighs on

The vehicle stability control (VSC) light and code P0420 are for two different problems. The VSC system would need to be tested for codes for that system. The code P0420 is for the O2 sensor or problem with...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
How to Renew Your Car Registration in Oklahoma(DELETED)
Having your car registered with the Oklahoma Tax Commission is an important part of driving legally in this state. You will need to do this within 30 days of moving to Oklahoma...
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...