How is fault code P0307 fixed?

A typical diagnostic sequence used by mechanics, provided here for educational reference only. Diagnostic work should be performed by a qualified mechanic with the appropriate tools and training. 1. Pull the codes and read the freeze frame data. Note whether you've also got P0300 or misfires on other cylinders, because a single P0307 points at one cylinder while a scatter of codes points at fuel pressure or a wider fault 2. Swap the cylinder 7 ignition coil with one from a known-good cylinder, clear the code, and drive it. If the misfire jumps to the cylinder you moved the coil to, you've found a dud coil 3. Pull and inspect the cylinder 7 spark plug. Look for oil fouling, a worn or wide gap, or a cracked insulator, and compare it against the plugs from the other cylinders 4. Check the cylinder 7 wiring, connector, and harness for green corrosion, chafing, or a loose pin before you condemn anything expensive 5. If ignition checks out, swap or test the injector for that cylinder. A blocked injector or one with a poor spray pattern will misfire under load 6. Last resort is a compression test on cylinder 7 against the rest. Low numbers here mean the fault is mechanical and you're into

Cylinder 7 Misfire Detected

Jump to the fix

Severity

High

Can I keep driving?

Avoid extended driving; visit a service soon.

First step

A typical diagnostic sequence used by mechanics, provided here for educational reference only. Diagnostic work should be performed by a qualified mechanic with the appropriate tools and training. 1. Pull the codes and read the freeze frame data. Note whether you've also got P0300 or misfires on other cylinders, because a single P0307 points at one cylinder while a scatter of codes points at fuel pressure or a wider fault 2.

PPowertrain
0Generic code
3Ignition / Misfire
07Sequence number

What does it mean?

A misfire is just what it sounds like; a cylinder that is not firing as it should. The P0307 code is caused by a misfire on the number seven cylinder. The Misfire monitor diagnostic is based on variation in crankshaft velocity. The PCM determines this information using the crankshaft position sensor and camshaft position sensor. A misfiring cylinder slows down momentarily, so by monitoring the cam and crank sensor signals, the PCM can calculate when a misfire occurs.

A P0307 code tells you only that a misfire has been detected, not WHY the cylinder is misfiring. That’s why with this code, a thorough diagnosis is mandatory. Misfire Monitor Different manufacturers implement OBD-II requirements slightly differently. The misfire monitor is an OBD-II procedure which identifies a misfire. The misfire monitor is a “continuous” monitor; it is always checking the crankshaft position sensor for a misfire.

It is important to note that the misfire monitor is very reliant on the crankshaft position sensor signal. A faulty crankshaft position sensor will misdiagnose misfires!

Symptoms

Likely causes

How to fix it

Codes From the Same System

All Fault Codes

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This information follows the generic OBD-II definition and does not replace a vehicle-specific diagnosis. The severity rating is rule-based; an authorised diagnostic reading is required for a definitive answer.