Skip the auto shop - Our mechanics make house calls

Q: Car misfires; crack in manifold

asked by on

My car is having multiple misfires. There is a crack in the manifold where the o2 sensor is.

Hello. A crack in the exhaust manifold near the O2 sensor can cause some poor sensor readings to the computer. The crack will allow fresh air to enter the exhaust, which causes the sensor to tell the computer that there is too much oxygen. This will send a message the computer to add more fuel, thus causing misfires. If the engine is running rough and misfiring without any actual misfire codes, then the crack may be the problem and the manifold will need to be replaced by a trained technician. A mechanic would typically scan the computer for any codes and see what the fuel trim readings are in order to be able to verify that the crack is the issue. If you do not have the tools to do this or don’t feel comfortable doing this type of repair, I would recommend the assistance of a certified mechanic that can replace any components causing problems in your vehicle.

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・Fair and transparent pricing

Get a quote

What others are asking

Q: Why does my check engine light come on when it's close to getting an oil change

Hi there. In most cases, a service engine light will be illuminated on the dashboard when routine service and maintenance is required. The Service (or Service Engine) light is a warning light that is connected to the engine control unit...

Q: Check Engine light; upstream O2 sensor

Hi there. If you have a code for the upstream O2 sensor then that is the most likely problem. Knowing the code would help me to be able to tell for sure what is going on. If you replaced the...

Q: My 2002 Honda Odyssey has a Check Engine light. It's supposed to be a misfire. The mechanic adjusted valves and changed coils but the issue remains

Hello. What problem code is stored for the Check Engine light? Hopefully all the plugs and all the coils were changed. If there was oil leaking (from the valve cover gasket) onto the plugs or rubber coil boots, this can...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
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...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.