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.

A: Hello. A crack in the exhaust manifold near...

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

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: Should I change my rotors?

If your rotors do not have a good clean smooth surface for the new pads to ride on then the pads will not be able to seat properly. This can lead to vehicle pull to one side or lack of...

Q: Serpentine Belt

It is recommended to replace the timing belt at 100k miles and the water pump and tensioner should be replaced at that time also. Do not confuse the timing belt from the accessory drive serpentine belt. The timing belt is...

Q: The 3rd and 4th cylinder are fouling the spark plugs. What could be the problem?

Hello there, it sounds like you have several different issues going on with your 1989 Chevrolet S10. You did great replacing the spark plugs to address the misfire issue as this commonly is the cause. If the problem persists or...

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...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...
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.