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: What causes Cylinder misfire? Spark plugs, wires and coil pack already replaced 2005 Dodge Stratus

Hello - in addition to the components which deliver spark on command (which you have already replaced), are the components which determine when the spark should be delivered (crankshaft and camshaft position sensors). A bad fuel mixture will cause misfire...

Q: Q: Why does my car keep stalling?

Hi There, I believe you may have a dirty or faulty mass air flow sensor. The mass air flow sensor monitors air intake as it is mixed with fuel prior to being injected into the motor. This sensor relays vital...

Q: What are the symptoms of a drive shaft going out on a 01 Subaru outback

Hello, thank you for writing in. First we shall address the symptoms of a "failing crankshaft". As there is a small chance the crankshaft itself is the cause of the vibration. The crankshaft is a solid metal shaft which would...

Related articles

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...
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.