How To Repair Pcv Pumping 07 Tahoe

What does OBD2 code P0300 mean?

P0300 definition: Random, Multiple Misfire Detected

P0300 indicates that two or more cylinders are experiencing misfires. A misfire occurs when an insufficient amount of fuel is burned in a cylinder. The efficient burning of fuel is essential to engine operation as the combustion of fuel is what provides the energy to power the engine. A misfire from two or more cylinders can be caused by many reasons from a faulty ignition system, fuel system, or internal engine failure. When P0300 occurs, it should be fixed immediately as long term driving with engine misfires could cause consequential damage to your engine and catalytic converter(s). Many times, P0300 occurs when there are worn-out spark plugs, spark plug wires, or a faulty ignition coil.

Code P0300 Severity – Severe

P0300 should be repaired immediately.

Consequences of continued driving

Ignoring this error could result in:

Ignition failure: Cutting off power to the ignition and fuel systems, causing the engine to stall and preventing further travel
Catalytic converter damage: Leading to poor engine performance and eventually engine shutdown that prevents transportation
Unsafe/dangerous conditions while operating the vehicle that could put the driver and others at risk

WARNING!

Continued driving with this code is NOT recommended. Find a repair shop or follow the steps below for further diagnosis.

OBD2 code P0300 symptoms

Check Engine Light is on or flashing
Engine runs rough, hesitates, or jerks when accelerating
Drivers may not notice any adverse conditions when driving
In some cases, drivers may experience decreased fuel economy, fuel smell from exhaust, rough idling, or lack of power from the engine

Commonly associated with codes: P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308

How do I fix code P0300?

The most common reason for engine code P0300 is faulty or worn spark plugs and/or spark plug wires.

>>> RELATED : How to replace spark plugs

>>> RELATED : Average cost to replace spark plugs

Other common P0300 causes and fixes

Ignition issues, including failing or damaged ignition coils
Distributor failure
Faulty fuel injector
Vacuum leak
Low fuel pressure
Camshaft and/or crankshaft sensor defective
Engine timing off
Leaking head gasket
Low engine compression
Poor quality fuel that is old or contaminated

How much does it cost to fix code P0300?

For error code P0300, one or more of the below repairs may be needed to solve the underlying issue. For each possible repair, the estimated cost of repair includes the cost of the relevant parts and the cost of labor required to make the repair. These prices are based on national averages. Your cost may differ depending on your location. Click on the links to learn more about each repair.

Spark plugs cost: $66-$250 (depending on if you take it to the shop or do it yourself)
Ignition Coils: $230-$640 (some cars require Intake manifold removal)
Spark plug wires: $180-$240
Fuel injectors: $1500-$1900
Vacuum leak: $100-$200
Fuel pump: $1300-$1700
Fuel pressure regulator: $200-$400

Can I fix code P0300 myself?

Code P0300 is considered an intermediate level diagnosis and repair for most DIYers. Watch the video below and follow the steps to diagnose and fix this fault code or schedule repairs so you can get back on the road.

Right repairs, right prices

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Code P0300 diagnosis steps:

So you've got a check engine light and have discovered error code P0300. Along with that light on the dash, you may be experiencing the engine running rough, sputtering, and you've maybe even noticed bad gas mileage.

Watch this video and follow the steps below to diagnose and fix code P0300 so you can get back on the road.

DIY difficulty level: 2/5 (Intermediate)

Tools/parts needed (our top picks from Amazon):

Screwdrivers
FIXD
Digital multimeter
5/8in. Spark Plug Socket
Ratchet, sockets, and extensions
Fuel pressure gauge
Compression tester
Leakdown tester
Spark plugs
Spark plug wires

Step 1: Use FIXD to ensure no other engine codes are present.

Use FIXD to scan your vehicle to verify P0300 is the only code present. If other codes are present, they must be addressed first.

Step 2: Check for loose connectors or damaged wiring at the ignition coils.

Look for loose engine ground wires as well. These can cause random misfire conditions. Tighten or connect where necessary.

Step 3: Check the condition of your spark plugs and spark plug wires.

Worn and old spark plug wires are common causes of random misfires. Replace spark plugs and wires if needed and recheck for misfires.

>>> LEARN: How to replace spark plugs in 4 easy steps

>>> LEARN : How to identify a fouled spark plug

>>> LEARN: How to test spark plug wires

>>> LEARN: How to gap spark plugs

Step 4: Check to ensure your engine is getting the proper amount of fuel.

If you have determined that your ignition system is operating correctly, there may be a problem within your fuel system that is causing the random misfires. The following should be checked to ensure the engine is getting the proper amount of fuel.

Check fuel pressure: Low fuel pressure can cause intermittent misfires on multiple cylinders. When the pressure is below the specification, the engine does not receive the proper amount of fuel and will start to lean misfire. The fuel pump or fuel pressure regulator could be the source of the low fuel pressure.

>>> LEARN: How to check fuel pressure

Check fuel injectors: Make sure the fuel injectors are functioning properly and activating. Random misfires can be a sign of faulty or clogged fuel injectors that need to be replaced. Also, check that the fuel injector wiring is not damaged and is connected properly.

>>> LEARN: How to check fuel injectors by ear

>>> LEARN: How to check fuel injectors with a digital multimeter

Step 5: Perform engine compression and leakdown test

If the ignition system and fuel system checks out, you may want to perform an engine compression test and leakdown test to see if there are any mechanical problems causing your misfire.

Common mechanical problems that can cause misfires:

Leaking Head Gasket
Broken valve spring
Broken piston ring
Worn valve guides
Burned valve
Timing chain or belt skipped tooth and engine is off time.

Common P0300 diagnosis mistakes

Loose fitting electrical connectors and broken or disconnected vacuum hoses are often overlooked. Oxygen sensor(s) are another common misdiagnosis for P0300.

Still need help fixing code P0300?

If you've followed the steps above and are still experiencing misfires or check engine code P0300, please contact the FIXD Mechanic Hotline if you're a FIXD Premium subscriber or find a RepairPal certified shop near you to get the right repairs at a fair price.

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