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: misfire under load

Hello. Engine misfires can be caused by many things. If the issue occurs under heavy load it may be possible that the vehicle requires a tune up. If the spark plugs are the originals, it may be possible that they...

Q: tachometer.speedometer temp gauge not working

If cluster fuses are good, check/clean the battery ground, bot the terminal and where the ground cable connects to the chassis. If that doesn't help, then you have a bad instrument cluster and it will have to be replaced. ...

Q: Q: White smoke out tailpipe.

If there was oil splattered all over the bottom of the vehicle, there is a good chance that the smoke you are seeing may just be excess oil that is being burnt off of the hot motor and exhaust. To...

Related articles

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...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
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.