AutoCodes – Toyota – P0308 Toyota

P0308 Toyota Code - Cylinder 8 Misfire Detected

Quick Answer

When the engine misfires, high concentrations of Hydrocarbons (HC) enter the exhaust gas. Common causes include Intake air leak, Faulty spark plug #8, Faulty ignition coil #8. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P0308 Toyota indicates Cylinder 8 Misfire Detected.
Common causes: Common causes include Intake air leak, Faulty spark plug #8, Faulty ignition coil #8.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 15,608

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Aug 25, 2022

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0308 Toyota Description

When the engine misfires, high concentrations of Hydrocarbons (HC) enter the exhaust gas. Extremely high hydrocarbon concentration levels can cause an increase in exhaust emission levels. Extremely high concentrations of hydrocarbons can also cause increases in the three-way catalytic converter temperature, which may cause damage to the three-way catalytic converter. To prevent this increase in emissions and to limit the possibility of thermal damage, the Engine Control Module (ECM) monitors the misfire count. When the temperature of the three-way catalytic converter reaches the point of thermal degradation, the ECM blinks the MIL. To monitor misfires, the ECM uses both the camshaft position sensor and the crankshaft position sensor. The camshaft position sensor is used to identify any misfiring cylinders and the crankshaft position sensor is used to measure variations in the crankshaft rotation speed. Misfires are counted when the crankshaft rotation speed variations exceed predetermined thresholds. If the misfire count exceeds the threshold levels and could cause emission control system performance deterioration, the ECM illuminates the MIL and stores a Diagnostic Trouble Code (DTC).

OBDII Code P0308 Toyota - Cylinder 8 Misfire Detected - AutoCodes.com — P0308 Toyota Code - Cylinder 8 Misfire Detected

What does this mean?

What are the Possible Causes of the DTC P0308 Toyota?

Intake air leak
Faulty spark plug #8
Faulty ignition coil #8
Clogged or faulty fuel injector #8
Fuel injectors #8 harness is open or shorted
Fuel Injectors #8 circuit poor electrical connection
Ignition coils #8 harness is open or shorted
Ignition coils #8 circuit poor electrical connection
Incorrect Fuel pressure
Faulty Mass Air Flow (MAF) Sensor
Faulty Engine Control Module (ECM)
Faulty Engine Coolant Temperature (ECT) Sensor

How to Fix the DTC P0308 Toyota?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

The P0308 code means that cylinder #8 is misfiring or is randomly misfiring. Start by checking for intake leaks and if no leaks are found the next step is to replace the spark plugs on cylinder #8. If the problem persists more tests need to be done to diagnose the problem. See "Possible Causes" for the most common problems.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0308 Toyota code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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Need Help with the Code?

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0308 Toyota Code

1. What are the common symptoms of OBDII code P0308 (Cylinder 8 Misfire Detected) in a Toyota?

Common symptoms include engine misfires, rough idle, loss of power, decreased fuel efficiency, and potentially increased emissions.

2. What are the typical causes of OBDII code P0308 in a Toyota?

The misfire in cylinder 8 could be caused by issues such as faulty ignition coils, spark plugs, fuel injectors, vacuum leaks, low compression, or engine timing problems.

3. How can I diagnose the cause of OBDII code P0308 in my Toyota?

Diagnosing the issue may involve performing a compression test, inspecting spark plugs and ignition components, checking fuel injectors, scanning for other codes, and conducting a visual inspection for any visible issues.

4. Can I continue driving my Toyota with OBDII code P0308 (Cylinder 8 Misfire Detected)?

It is not recommended to drive the vehicle with a misfiring cylinder as it can lead to further damage to the engine and emission control system. Immediate attention and repair are necessary.

5. What is the typical repair process for resolving OBDII code P0308 in a Toyota?

The repair process may involve replacing faulty ignition coils, spark plugs, fuel injectors, fixing vacuum leaks, addressing compression issues, adjusting engine timing, or performing other necessary repairs based on the diagnosis.

6. Are there any maintenance tips to prevent OBDII code P0308 in my Toyota?

Regular maintenance, such as timely spark plug replacements, fuel system cleaning, and overall engine health checks, can help prevent issues that lead to cylinder misfires and OBDII codes.

7. Is it possible for a DIY enthusiast to fix OBDII code P0308 in a Toyota?

Depending on the mechanical skills and tools available, some DIY enthusiasts may be able to address simpler causes of the misfire, such as replacing spark plugs. However, more complex issues may require professional diagnosis and repair.

8. Can environmental factors contribute to OBDII code P0308 in a Toyota?

Extreme weather conditions, such as very high or low temperatures, humidity levels, or driving in dusty environments, can affect engine performance and potentially lead to misfires triggering the OBDII code P0308.

9. How long can I wait before addressing OBDII code P0308 in my Toyota?

It is best to address the issue as soon as possible to prevent further damage to the engine and ensure optimal performance and fuel efficiency. Delaying repairs can lead to more severe problems over time.

10. Does clearing the OBDII code P0308 in my Toyota reset the issue?

Clearing the code without addressing the underlying cause will not fix the problem. The misfire in cylinder 8 needs to be diagnosed and repaired to prevent the code from reappearing.