Q: EGR code, Cylinder 4 misfire code 0304 detected.

asked by on

In the winter I sometimes got an EGR code then it would go away. Replaced the EGR valve with cheap China one now getting Cylinder 4 misfire. I got a slightly used supposedly known good one from eBay (looks decent) same 304 code. If I block off the EGR tube 304 code goes away but get EGR code. I changed the ECT and IAT sensors thinking the ECM does not know the engine is warm and may be keeping the EGR open. What could be causing this? Head gasket? I know the EGR takes from cylinder 4 in this engine, should the EGR fully close when the engine is warm or does it stay slightly open all the time?

My car has 208500 miles.
My car has an automatic transmission.

Hi there. The Exhaust Gas Recirculation (EGR) valve may be not designed for the emissions requirements for U.S. standards. If the EGR is pulling from cylinder number 4 and after replacing the EGR and the computer detects a misfire, then the EGR is malfunctioning and not responding. When you close off the tube to the EGR and the EGR light comes on and the misfire light goes out, then the EGR is not responding to your emissions system. I recommend replacing the EGR with the OEM specified part for the engine and all of the issues should go away. If you need further assistance with your misfire and EGR, then seek out a professional, such as one from Your Mechanic, to help you.

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. EGR code, Cylinder 4 misfire code 0304 detected.

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: I have code P0305 on it. Ive heard it's cylinder #5 misfiring but I don't know what the issue may be.

The code P0305 is indication that cylinder number 5 is not firing all the time. When you see the check engine light flashing then the cylinder is actively misfiring. You should have the spark plug and coil checked for problems...

Q: My battery is brand new but my car won't start. I tried hitting the starter with a hammer and nothing changed. My car is turning o

Just by pouring Coke on cables do not clean the cables enough to get good voltage to the starter. I suggest you have the cables and clamps cleaned properly and if still will not crank then have the new battery...

Q: Brake Pulsation

You may have a bent rotor hub. This can be checked with a dial indicator gage and if hub is bent more than 10 thousands of an inch it will cause the rotor to move back and forth and cause...

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...
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...
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.