P0308 Code: Meaning, Symptoms, Causes & Fix

Overview

P0308 is triggered when monitoring logic identifies an issue with Cylinder 8 Misfire Detected affecting powertrain controls.

Symptoms

reduced performance
increased fuel use
check engine light

Common causes

Control module logic or calibration issue affecting cylinder 8 misfire detected
Electrical fault in the affected circuit
Connector pin damage/corrosion or harness stress near related components

How to diagnose P0308

Confirm P0308 and capture freeze-frame data with a professional scan tool.
Inspect wiring, connectors, and grounds related to cylinder 8 misfire detected for obvious defects.
Use freeze-frame and live data to isolate whether the issue is electrical, mechanical, or control logic.
Check for related DTCs to identify the root-cause chain before replacing parts.
After repair, clear codes and confirm readiness monitors complete without recurrence.

Severity of code P0308

High: This code is high severity because the affected system can directly impact drivability, safety, or catalyst/engine protection.

Can you drive with P0308?

Driving with P0308 should be limited to a short trip for diagnosis/repair. Continued driving can cause expensive secondary damage.

If the warning lamp is flashing or drivability/safety is affected, avoid driving and diagnose immediately.

How to fix it (step-by-step)

Repair obvious wiring/connector faults first to prevent repeat parts replacement.
Address the root fault mode (generic) in the cylinder 8 misfire detected circuit/system.
Apply the required relearn/adaptation procedure if specified by service information.
Road-test and verify P0308 remains cleared under the conditions that originally set the code.

Fix options

Inspect circuit and connector condition.
Test component operation and replace if faulty.
Clear DTCs and verify with live data and completed drive cycle.

Typical repair cost

$400-$2000

Common mistakes when diagnosing P0308

Replacing parts without verifying voltage, ground, and signal integrity first.
Ignoring related stored/pending codes that indicate upstream faults.
Skipping post-repair verification drive cycle and readiness checks.

P0308 in common vehicles

P0308 appears across makes such as BMW, Mercedes-Benz, Audi, Volvo. Failure patterns differ by platform: wiring routes, software calibration, and component supplier revisions can change root cause.

Frequently asked questions

What causes P0308?

P0308 is commonly set by generic faults affecting cylinder 8 misfire detected.

How much does it cost to fix P0308?

For P0308, repair costs are typically $400-$2000 depending on exact root cause, labor rates, and part quality.

Can I clear P0308 without repair?

You can clear P0308 temporarily, but the code usually returns until the underlying fault is corrected.