# P0304 on the 2027 Jeep Grand Cherokee L

The bulletins listed name this code in NHTSA's summary, or are about the same components. A bulletin or a recall listed here may apply to the model year. None of it is a diagnosis.

Nobody has written a description of this code yet.

## Bulletins for this model year that name P0304

- [11037570](https://open.wenmarpro.com/bulletins/11037570), 2026-09-30: Umbrella Valve Seal Missing From Cylinder Head Cover Vehicle may exhibit a MIL\-ON. SYMPTOM: Upon inspection the technician may find that one or more of the following Diagnostic Trouble Codes \(DTCs\) have set: ● P0300\-00 \- Random/Multiple Cylinder Misfire Detected. ● P0301\-00 \- Cylinder 1 Misfire. ● P0302\-00 \- Cylinder 2 Misfire. ● P0303\-00 \- Cylinder 3 Misfire. ● P0304\-00 \- Cylinder 4 Misfire. This bulletin involves inspecting for a missing umbrella valve seal on the underside of the cylinder head cover and, if necessary, replacing the cylinder head cover.
- [11036358](https://open.wenmarpro.com/bulletins/11036358), 2026-08-26: Umbrella Valve Seal Missing From Cylinder Vehicle may exhibit a MIL\-ON. SYMPTOM: Upon inspection the technician may find that one or more of the following Diagnostic Trouble Codes \(DTCs\) have set: ● P0300\-00 \- Random/Multiple Cylinder Misfire Detected. ● P0301\-00 \- Cylinder 1 Misfire. ● P0302\-00 \- Cylinder 2 Misfire. ● P0303\-00 \- Cylinder 3 Misfire. ● P0304\-00 \- Cylinder 4 Misfire. This bulletin involves inspecting for a missing umbrella valve seal on the underside of the cylinder head cover and, if necessary, replacing the cylinder head cover.
- [11036357](https://open.wenmarpro.com/bulletins/11036357), 2026-08-26: Umbrella Valve Seal Missing From Cylinder Head Cover Customer may experience a MIL\-ON and/or an indication of low engine oil level. SYMPTOM: Upon inspection the technician may find the following: 1. One or more of the following Diagnostic Trouble Codes \(DTCs\) have set: ● P0300\-00 \- Random/Multiple Cylinder Misfire Detected. ● P0301\-00 \- Cylinder 1 Misfire. ● P0302\-00 \- Cylinder 2 Misfire. ● P0303\-00 \- Cylinder 3 Misfire. ● P0304\-00 \- Cylinder 4 Misfire. 2. Engine oil level is low. IMPORTANT\! If none of above symptoms are present, this TSB does NOT apply. This bulletin involves inspecting the engine oil level, possibly inspecting for a missing umbrella valve seal on the underside of the cylinder head cover and, if necessary, replacing the cylinder head cover.
- [11036158](https://open.wenmarpro.com/bulletins/11036158), 2026-08-13: Umbrella Valve Seal Missing From Cylinder Head Cover Customer may experience a MIL\-ON and/or an indication of low engine oil level. SYMPTOM: Upon inspection the technician may find the following: 1. One or more of the following Diagnostic Trouble Codes \(DTCs\) have set: ● P0300\-00 \- Random/Multiple Cylinder Misfire Detected. ● P0301\-00 \- Cylinder 1 Misfire. ● P0302\-00 \- Cylinder 2 Misfire. ● P0303\-00 \- Cylinder 3 Misfire. ● P0304\-00 \- Cylinder 4 Misfire. 2. Engine oil level is low. IMPORTANT\! If none of above symptoms are present, this TSB does NOT apply. This bulletin involves inspecting the engine oil level, possibly inspecting for a missing umbrella valve seal on the underside of the cylinder head cover and, if necessary, replacing the cylinder head cover