AutoCodes – GMC – P0301 2018 GMC Sierra

P0301 2018 GMC Sierra Code - Cylinder 1 Misfire Detected

Quick Answer

A misfiring cylinder causes slight variations in the rotational speed of the crankshaft. Common causes include Faulty Spark Plug #1, Clogged or faulty Fuel Injector #1, Faulty Ignition Coil #1. 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: P0301 2018 GMC Sierra indicates Cylinder 1 Misfire Detected.
Common causes: Common causes include Faulty Spark Plug #1, Clogged or faulty Fuel Injector #1, Faulty Ignition Coil #1.
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 410

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 Jul 21, 2022

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0301 2018 GMC Sierra Description

A misfiring cylinder causes slight variations in the rotational speed of the crankshaft. The Engine Control Module (ECM) can detect these variations by closely monitoring the crankshaft position sensor signal. The signals of the camshaft position sensors are used to determine which cylinder is misfiring. If the ECM detects a misfire rate sufficient to cause emission levels to exceed mandated standards, the Diagnostic Trouble Code (DTC) will be set. Under certain driving conditions, a misfire rate can be high enough to cause the catalytic converter to overheat, damaging the converter. The Malfunction Indicator Lamp (MIL) flashes when the converter is overheating, damaging conditions are present, and the DTC is set. The DTC will be set when the ECM detects a crankshaft rotation speed variation indicating a single-cylinder misfire rate sufficient to cause emissions levels to exceed mandated standards.

OBDII Code P0301 2018 GMC Sierra - Cylinder 1 Misfire Detected - AutoCodes.com — P0301 2018 GMC Sierra Code - Cylinder 1 Misfire Detected

What does this mean?

What are the Possible Causes of the DTC P0301 2018 GMC Sierra?

Faulty Spark Plug #1
Clogged or faulty Fuel Injector #1
Faulty Ignition Coil #1
Fuel Injector #1 harness is open or shorted
Fuel Injector #1 circuit poor electrical connection
Ignition Coil #1 harness is open or shorted
Ignition Coil #1 circuit poor electrical connection
Insufficient cylinder 1 compression
Incorrect fuel pressure
Intake air leak

How to Fix the DTC P0301 2018 GMC Sierra?

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 P0301 code means that cylinder #1 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 #1. 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 P0301 2018 GMC Sierra 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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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 P0301 2018 GMC Sierra Code

1. What are the common symptoms of OBDII code P0301 (Cylinder 1 Misfire Detected) on a 2018 GMC Sierra?

- Common symptoms include rough idling, engine vibration, loss of power, and potential hesitation or jerking while accelerating.

2. What are the possible causes of a cylinder 1 misfire in a 2018 GMC Sierra triggering code P0301?

- Possible causes include faulty ignition system components, clogged fuel injector, vacuum leaks, low compression in cylinder 1, or a damaged spark plug.

3. How can I diagnose the cause of the cylinder 1 misfire in my 2018 GMC Sierra with code P0301?

- To diagnose the issue, you can perform a thorough inspection of spark plugs, ignition coils, fuel injectors, and vacuum lines. Additionally, conducting a compression test on cylinder 1 can help pinpoint the problem.

4. Can a dirty or clogged fuel injector cause OBDII code P0301 in a 2018 GMC Sierra?

- Yes, a dirty or clogged fuel injector can lead to a lean or rich condition in cylinder 1, causing a misfire and triggering code P0301.

5. How can I repair a cylinder 1 misfire detected in my 2018 GMC Sierra with OBDII code P0301?

- Repair steps may include replacing the spark plug, ignition coil, fuel injector, or addressing any vacuum leaks. Additionally, performing a compression test and addressing low compression in cylinder 1 may be necessary.

6. Is it safe to continue driving my 2018 GMC Sierra with OBDII code P0301 (Cylinder 1 Misfire Detected)?

- It is not recommended to drive the vehicle with a misfire as it can lead to further damage to the engine and emission components. Immediate diagnosis and repair are advised.

7. How much does it typically cost to repair a cylinder 1 misfire in a 2018 GMC Sierra triggering code P0301?

- The cost of repair can vary depending on the exact cause of the misfire. Costs may range from replacing a spark plug or ignition coil to more extensive repairs involving the fuel system or engine components.

8. Can a bad spark plug be the sole reason for OBDII code P0301 on a 2018 GMC Sierra?

- Yes, a bad or fouled spark plug in cylinder 1 can cause a misfire and trigger code P0301. It is one of the common culprits for this issue.

9. Will resetting the OBDII code P0301 on my 2018 GMC Sierra make the issue go away?

- Resetting the code will clear the check engine light temporarily, but if the underlying issue causing the misfire is not addressed, the code is likely to return as the problem persists.

10. How important is it to fix a cylinder 1 misfire in a 2018 GMC Sierra with OBDII code P0301 promptly?

- It is crucial to address the misfire promptly to prevent potential damage to the engine and ensure optimal performance and fuel efficiency of the vehicle.