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

asked by on December 27, 2016

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.

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


Experienced Mechanic?

Earn up to $70/hr

What others are asking

How do I deactivate the auto call transfer function on the HandsFreeLink?
Your HandsFreeLink® (HFL) system can automatically transfer a call from your cell phone to the car if the key is set to I or II. However, you can change it so that the system doesn’t automatically transfer the call. To...
Rattling while driving on rough or bumpy roads
Hello. It sounds like you may have a bearing that is failing (https://www.yourmechanic.com/article/symptoms-of-bad-or-failing-wheel-bearings), or there is a loose brake pad (https://www.yourmechanic.com/article/symptoms-of-bad-or-failing-brake-pads). It is common for the brake hold down clips to become worn and then this noise occurs. These need...
Why does my Rolls Royce Ghost make a knocking noise when turning
Hello. Typically this noise will occur on full turn when you have the wrong size wheels on it or if it has a worn out ball joint. Most of the time this is caused by a ball joint. The vehicle...
Why would my check engine light come on in my 2005 Honda Fit after it was serviced
Hello. It is not normal for the check engine light to come on after being serviced. Either something was not installed correctly or one of the parts is wrong. It may also be something completely different. I usually start by...
Lost coolant through the exhaust
If you are losing coolant out of the exhaust after you overheated the motor then you may have damaged the heads by warping them and coolant now leaks past the head gaskets. Your engine will not crank now due to...
Key won't turn in the ignition switch.
Hi there. If the key can go into the ignition switch and turn then the key is the right one. If the switch is not turning all the way, then the switch is damaged and needs replaced with the key...
Mobil 1 no longer meets BMW LL-01 spec. Do you have Castrol Edge 0W-40 Euro Formula available?
Any oil that you desire can be used in an oil change and the customer can, of course, supply the oil himself or herself. I see Castrol Edge OW-40 European formula vended at Amazon, and elsewhere, and thus you can...
I just put new spark plug in my car with new spark plug caps for my 2004 chevy malibu classic but my car wont start? Someone help
Hi there. Assuming you correctly gaped the spark plugs as recommended by the manufacturer, and installed the plug wires correctly, it's likely that this is due to an electrical relay that may have been damaged (especially if you did not...
Need to install new wiper switch on my 1966 chevelle SS
Hi Charles. Thanks for the question today. If I recall correctly, the wiper switch on the driver side of the dash does require removal of the dash, as I don't think you can access it from behind the firewall. It's...

Related articles

2012 Toyota Camry vs. 2012 Chevrolet Malibu: Which One Should I Buy?
Mid-size sedans are the perfect family vehicle; offering just enough space for you and a few kids, but not so much that a small family will feel lost in them. This class of vehicles is slightly larger than a compact...
The Best Used Cars to Buy If You Just Retired
Here’s Here’s a cruel, hard fact – car manufacturers no longer target seniors. Instead, they devote their time and energy to appealing to the 18-45 demographic. Still, some features make certain cars more suitable for older drivers. We have evaluated...
The Best Used Cars to Buy If Safety is #1
Maybe Maybe you’re a parent buying the first car for your teenager, or perhaps you’re a new parent and the safety of your little one is of the utmost importance. Or perhaps you're a safety-minded individual looking to make a...