Your Grand Caravan threw P0303, and you are probably already thinking about spark plugs. Good instinct. But here is what catches a surprising number of Grand Caravan owners: cylinder 3 is not where you might think it is, and working on the wrong cylinder is extremely common with this engine. Before you do anything, you need to know exactly where cylinder 3 is on your specific engine.
On the Dodge Grand Caravan 3.3L and 3.8L V6, cylinders are numbered 1-3-5 on the rear bank (the bank closest to the firewall) and 2-4-6 on the front bank (facing you when you open the hood). Cylinder 3 is the middle cylinder on the rear bank. On the 3.6L Pentastar V6 in the newer Grand Caravans (2011 onward), cylinder 3 is also on the rear bank. That rear bank location is critical because it affects how you access the plug, the coil, and the injector for diagnosis and repair.
Why Cylinder 3 Matters and What P0303 Is Telling You
P0303 means cylinder 3 is misfiring. The PCM monitors crankshaft speed variations using the crankshaft position sensor. When one cylinder fires consistently, the crank accelerates smoothly with each power stroke. When cylinder 3 fails to fire, the crank speed drops at that point in the rotation. The PCM detects this hesitation and logs P0303. If the misfire is severe enough to cause a rapid flashing of the check engine light, unburned fuel is entering the exhaust and damaging the catalytic converter right now. In that case, stop driving and do not drive further until the misfire is resolved.
P0303 by itself on a Grand Caravan almost always traces back to one of three things: a worn spark plug, a failed ignition coil (coil-on-plug on newer engines, a coil pack on older ones), or a clogged or failed fuel injector. The coil swap test is the fastest way to determine which one it is.
How to Fix P0303 Cylinder 3 Misfire on Dodge Grand Caravan
Step 1: Confirm You Are Working on the Right Cylinder
Before touching anything, verify which physical location cylinder 3 corresponds to in your engine. On all Grand Caravan V6 engines, cylinder 3 is the center cylinder on the rear bank. The rear bank faces the firewall and is significantly harder to access than the front bank. You will likely need to remove the engine cover and possibly the upper intake manifold to reach the rear bank plugs and coils on the 3.6L Pentastar.
On the 3.3L and 3.8L V6 (Pre-2011 Grand Caravan)
These engines use a coil pack system with a single coil pack driving multiple cylinders rather than individual coil-on-plug units. The coil pack for cylinders 1, 3, and 5 is on the rear. To access cylinder 3 on these engines, you will need to remove the air intake components to reach the rear of the engine. The spark plugs on the rear bank are accessible with a long extension and a universal swivel joint. Allow time for this: it is not a difficult job but it requires patience with access.
On the 3.6L Pentastar V6 (2011 Onward Grand Caravan)
The Pentastar uses individual coil-on-plug units for each cylinder. Cylinder 3 is accessed from the rear bank. On many Grand Caravan applications, the upper intake manifold must be removed to reach the rear bank coils and plugs comfortably. This adds 30 to 45 minutes to the job but is not a reason to take it to a shop unless you are not comfortable with the disassembly. The manifold bolts torque spec is approximately 89 inch-pounds, and new gaskets should be used on reinstallation.
Step 2: The Coil Swap Test: The Fastest Diagnostic You Can Do
Rather than replacing parts one at a time and hoping the code goes away, the coil swap test tells you definitively whether the ignition coil is the problem in about five minutes. This works on the 3.6L Pentastar with individual coil-on-plug units.
How to Do the Coil Swap Test
Access cylinder 3 and the adjacent cylinder (for example, cylinder 5 on the rear bank). Disconnect both coil connectors. Swap the two coils: put cylinder 3’s coil on cylinder 5, and put cylinder 5’s coil on cylinder 3. Reconnect both, clear the P0303 code, and drive normally for 10 minutes. Scan for codes again. If the misfire has moved from P0303 to P0305, the coil you moved is the failed part: replace it. If the code stays as P0303, the coil is not the problem, and you need to look at the spark plug or injector for cylinder 3.
If the Coil Swaps Out Clean
With the coil confirmed good, replace the cylinder 3 spark plug. On high-mileage Grand Caravans, a contaminated or worn plug can cause a persistent misfire on one cylinder that no coil replacement will fix. Pull the existing plug: excessive carbon, oil fouling, or a cracked porcelain insulator confirms a plug-related misfire.
Step 3: Testing the Fuel Injector for Cylinder 3
If the coil is good and the plug is good and P0303 persists, the fuel injector for cylinder 3 is the next suspect. A clogged or electrically failed injector delivers insufficient or no fuel to that cylinder. On the Grand Caravan, a combination of P0303 and P0171 (system too lean) often accompanies an injector that is underperforming on fuel delivery.
How to Test the Injector
Use a mechanic stethoscope or a long screwdriver held to the injector body and your ear to the handle. A functioning injector clicks audibly with each firing pulse at idle. No click from cylinder 3 while adjacent injectors click normally indicates an electrical failure or a clogged injector. You can also test injector resistance with a multimeter: disconnect the injector connector and measure resistance across the two terminals. Most Chrysler/Dodge injectors measure 12 to 16 ohms. An OL reading confirms an open circuit in the injector coil.
Stuck Rocker Arm on the 3.6L Pentastar
If you drive a 2011 or newer Grand Caravan with the 3.6L Pentastar and the P0303 is accompanied by a ticking noise from the engine, there is a specific and well-documented failure mode unique to this engine: stuck or collapsed rocker arms. The Pentastar uses a Multi-Displacement System (MDS) on some applications, and the rocker arm lifter mechanism can fail on high-mileage engines.
A failed rocker on cylinder 3 causes a persistent misfire that no plug or coil replacement will resolve, and a ticking or tapping sound is the giveaway. A compression test on cylinder 3 will confirm this: low compression compared to other cylinders points at a mechanical fault, not an ignition or fuel problem.
What to Try | Test Method | Cost of Fix | Move to Next Step If… |
|---|---|---|---|
Spark plug | Visual inspection; compare to other plugs | $5-$15 per plug | Plug looks clean and code stays |
Ignition coil | Coil swap test: misfire follows coil? | $40-$80 per coil | Misfire stays on cylinder 3 after swap |
Fuel injector | Stethoscope click test; multimeter resistance | $60-$150 per injector | Injector clicks normally and resistance is good |
Compression test | Compression gauge on cylinder 3 | Shop test $50-$100 | Compression equal to adjacent cylinders |
Rocker arm (3.6L only) | Low compression + ticking = rocker arm suspect | $400-$900 at shop | N/A: this is the final step |
Frequently Asked Questions
Where is cylinder 3 on a Dodge Grand Caravan?
On all Dodge Grand Caravan V6 engines (3.3L, 3.8L, and 3.6L Pentastar), cylinder 3 is the center cylinder on the rear bank, the bank closest to the firewall. Cylinders 1, 3, and 5 are on the rear bank. Cylinders 2, 4, and 6 are on the front bank facing you when the hood is open. This location makes cylinder 3 harder to access than front bank cylinders and is a common source of confusion for DIYers.
Can I drive my Grand Caravan with P0303?
Not recommended. A constant misfire sends unburned fuel into the catalytic converter, which overheats and melts the substrate. A destroyed catalytic converter is an expensive consequence of ignoring a misfire. If the check engine light is flashing, pull over immediately. A steady light with P0303 means limit driving to getting to a shop within a day or two.
Why does P0303 keep coming back after I replaced the spark plug and coil?
If P0303 returns after confirmed coil and plug replacement, check the fuel injector for cylinder 3, inspect the wiring to that cylinder for corrosion or damage, and perform a compression test. On the 3.6L Pentastar, a recurring misfire with a ticking noise points to a mechanical valve train issue rather than an ignition or fuel problem.
The Bottom Line
P0303 on the Grand Caravan is a diagnosable problem, but the rear bank location of cylinder 3 means access matters and misidentifying the cylinder wastes time and money. Use the coil swap test as your starting point: it costs nothing and takes 10 minutes. If the misfire follows the coil, buy a coil. If it stays on cylinder 3, move to the plug and then the injector. And if the engine is making a ticking noise alongside the misfire, do a compression test before buying any more ignition parts.