AutoCodes – Hummer – P0302 Hummer

P0302 Hummer Code - Cylinder 2 Misfire Detected

Quick Answer

A misfiring cylinder causes slight variations in the rotational speed of the crankshaft. Common causes include Faulty Spark Plug #2, Clogged or faulty Fuel Injector #2, Faulty Ignition Coil #2. 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: P0302 Hummer indicates Cylinder 2 Misfire Detected.
Common causes: Common causes include Faulty Spark Plug #2, Clogged or faulty Fuel Injector #2, Faulty Ignition Coil #2.
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 9,407

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 P0302 Hummer 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 P0302 Hummer - Cylinder 2 Misfire Detected - AutoCodes.com — P0302 Hummer Code - Cylinder 2 Misfire Detected

What does this mean?

What are the Possible Causes of the DTC P0302 Hummer?

Faulty Spark Plug #2
Clogged or faulty Fuel Injector #2
Faulty Ignition Coil #2
Fuel Injector #2 harness is open or shorted
Fuel Injector #2 circuit poor electrical connection
Ignition Coil #2 harness is open or shorted
Ignition Coil #2 circuit poor electrical connection
Insufficient cylinder 2 compression
Incorrect fuel pressure
Intake air leak

How to Fix the DTC P0302 Hummer?

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 P0302 code means that cylinder 2 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 2. If the problem persists more tests need to be done to diagnose the problem, see "Possible Causes".

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0302 Hummer 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 P0302 Hummer Code

1. What are the common symptoms of OBDII code P0302 for a Hummer indicating a cylinder 2 misfire?

- Common symptoms include rough idling, loss of power, engine vibration, and potential fuel smell from the exhaust.

2. What are the typical causes of a cylinder 2 misfire in a Hummer triggering code P0302?

- The causes can vary and may include faulty spark plugs, a malfunctioning ignition coil, vacuum leaks, fuel injector issues, or low compression in cylinder 2.

3. How can I diagnose the source of a cylinder 2 misfire in my Hummer if I get code P0302?

- You can start by checking the spark plugs, ignition coil, and fuel injector for cylinder 2, inspecting for vacuum leaks, and performing a compression test on cylinder 2.

4. Is it safe to drive my Hummer with OBDII code P0302 indicating a cylinder 2 misfire?

- It is not recommended to drive the vehicle extensively with a misfire, as it can lead to further damage to the engine and catalytic converter.

5. Can a dirty fuel filter cause a cylinder 2 misfire in a Hummer triggering code P0302?

- Yes, a clogged or dirty fuel filter can restrict fuel flow to cylinder 2, leading to a misfire and triggering the OBDII code P0302.

6. What are some quick repair tips for addressing a cylinder 2 misfire in a Hummer with code P0302?

- Quick repair tips can include checking and replacing the spark plugs, inspecting the ignition coil, cleaning or replacing the fuel injector, and ensuring there are no vacuum leaks.

7. How important is it to address an OBDII code P0302 for a cylinder 2 misfire in a Hummer promptly?

- It is crucial to address the issue promptly to prevent further damage to the engine, ensure optimal fuel efficiency, and maintain overall vehicle performance.

8. Can a cylinder 2 misfire in a Hummer be caused by a faulty oxygen sensor even if the O2 sensor code is not present?

- While less common, a faulty oxygen sensor can impact fuel mixture, potentially leading to a cylinder 2 misfire without directly triggering an O2 sensor-related code.

9. Should I reset the OBDII code P0302 after addressing a cylinder 2 misfire issue in my Hummer?

- It is recommended to clear the code after addressing the misfire and performing necessary repairs. This allows you to monitor if the issue reoccurs.

10. How can regular maintenance help prevent cylinder misfire issues like code P0302 in a Hummer?

- Regular maintenance, such as timely spark plug replacements, fuel system cleaning, and periodic engine tune-ups, can help prevent cylinder misfire issues and maintain optimal engine performance.