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What P0305 means for your Jeep Grand Cherokee
Your Grand Cherokee dropped cyl 5. On the 3.6L Pentastar V6, cyl 5 is one of the right-bank (bank 2) cylinders - which is exactly where the notorious W77 cylinder head valve-seat erosion happens. P0305 on a 2011-2013 Pentastar is almost always the W77 head, and Chrysler TSB 09-001-13 extends the warranty to 10 yr/150k mi. CHECK YOUR VIN before paying. On the 5.7L Hemi, cyl 5 is NOT an MDS cylinder, so a Hemi P0305 is usually a clean coil swap.
Top Causes of P0305 on the Jeep Grand Cherokee
55%
#1 CAUSE
W77 Right-Bank Cylinder Head Valve Seat Erosion (3.6L Pentastar)
Cyl 5 is bank 2 (right) on the 3.6L Pentastar. The 2011-2013 W77 right head develops valve-seat erosion - exhaust valves drop compression on cyls 2, 4, 6 (and sometimes 5 by misfire firing pattern). Chrysler TSB 09-001-13 covers head replacement under extended warranty (10 yr/150k mi). If your VIN qualifies, the repair is FREE at a Mopar dealer. Out of warranty: $1,800-$2,800.
Head Under Warranty
$0 (TSB 09-001-13)
Out of Warranty
$1,800-$2,800
New W77 Head
$1,200-$1,800
25%
#2 CAUSE
Cylinder 5 COP Coil Failure (Hemi / Pentastar)
5.7L Hemi cyl 5 is rear-bank driver side - moderate access. NOT an MDS cylinder. Mopar 56028394AB (Hemi). On Pentastar, Mopar 4606824AC. Swap-test with coil 3 or 1 (firing-order adjacent).
OEM Coil
$70-$120
Aftermarket
$28-$55
w/Labor
$140-$240
15%
#3 CAUSE
Worn Plug or Carbon (Hemi 16-plug system)
Hemi runs 2 plugs per cylinder = 16 plugs total. Cyl 5 has two plugs. Spec is NGK ZFR5LP-13G. Most owners cheap out and replace only 8 - that causes repeat misfires. Replace all 16 at once.
Plugs Hemi (16)
$80-$140
w/Labor
$280-$520
Pentastar (6)
$40-$85
Most Affected Grand Cherokee Model Years
| Year | Engine | Primary Cause | Typical Mileage | Notes |
|---|---|---|---|---|
| 2011-2013 | 3.6L Pentastar V6 | W77 head | 60k-130k | TSB 09-001-13 free head |
| 2014-2018 | 3.6L Pentastar / 5.7L Hemi | Coil + W77 (lingering) | 60k-140k | W77 mostly resolved |
| 2019-2024 | 3.6L Pentastar / 5.7L Hemi eTorque | Coil pack #5 | 60k-120k | eTorque hybrid |
| 2015-2024 | 6.4L 392 Hemi | Coil pack #5 | 60k-140k | Clean coil job |
TSB info: Chrysler TSB 09-001-13 (W77 right-bank cylinder head defect 2011-2013 Pentastar, extended warranty 10 yr / 150k mi).
How to Diagnose P0305 on a Jeep Grand Cherokee
- On a 2011-2013 3.6L Pentastar with P0305, CHECK YOUR VIN against TSB 09-001-13 FIRST. The W77 head fix is FREE if you qualify (10 yr / 150k mi extended warranty).
- Do a compression test on bank 2 (cyls 2, 4, 6). If they read 15+% lower than bank 1, the W77 head is the cause regardless of code combination.
- If TSB doesn't apply or compression is fine, swap coil 5 with coil 3. Drive 20 miles. Code follows the coil = replace it.
Want a step-by-step walkthrough specific to your Jeep Grand Cherokee? Run a $5.99 AI diagnosis report - we narrow the cause to your year, engine, and symptoms.
P0305 Jeep Grand Cherokee FAQs
Is P0305 a W77 head problem on a Pentastar?
Very likely on 2011-2013 3.6L Pentastars. The W77 right-bank head valve-seat erosion causes bank-2 misfires - cyls 2, 4, 6 are most affected, but cyl 5 firing-order events can also trigger as compression drops on adjacent cylinders. Check TSB 09-001-13.
How do I get the free W77 head replacement?
Bring your Grand Cherokee to a Mopar/Jeep dealer with the misfire codes documented. Ask them to verify VIN coverage under TSB 09-001-13. Required: under 150k mi, under 10 years from in-service date, confirmed bank-2 compression issue.
Is the 5.7L Hemi P0305 serious?
Less so than Pentastar P0305. Cyl 5 is NOT an MDS cylinder, so it won't be the lifter-collapse catastrophe you see on cyls 1, 4, 6, 7. Usually a $140-$240 coil swap.
Should I trust a used Grand Cherokee with the 3.6L Pentastar?
2014+ models are much improved - W77 head defect mostly resolved. 2011-2013: only buy if you can confirm the heads were replaced under TSB 09-001-13. Get a pre-purchase compression test on bank 2.