$30 off over your first 3 services! $10 off 1st service + $10 off 2nd service + $10 off 3rd service.

Get Started


Causes, Symptoms, Severity and Cost

2006 lexus rx 400h 4dr suv hybrid fq oem 2 500

2006 Lexus RX 400h

Technical Description:

The engine is experiencing misfires from one or more of the engine’s cylinders.

What P0300 really means:

In the majority of these instances, this code is accompanied by a P0301, P0302, P0303, etc., which will designate the exact cylinder that is misfiring. The computer may also blink the check engine light to alert the driver to stop the engine as soon as possible that these conditions will cause damage to the catalytic converter.

What are the symptoms of a P0300 code?

The code tells us what is already known - the engine is running poorly. There is no avoiding the shaking or bucking or chugging from a misfiring engine, and if the driver does want to play hear no evil, the consequences could be quite expensive. Something is wrong with the fuel mixture, compression or spark within the cylinders, and if ignored the engine or catalytic converter could be heavily damaged.

What is the severity of a P0300 code?

Critical. The car should be brought in for repair as soon as possible with the same day being ideal. The list of reasons for a misfire is quite long, so dropping off the car should be expected, as an answer might not be easily found.

What is the cost to resolve a P0300?

  • Estimated diagnostic cost = $100
  • Estimated part(s) + labor cost = $250-900 (depending on specific part to be replaced)

The cost for a misfire can range widely from car to car. At the very least expect to pay around $100 for a diagnostic check to find out the problem. The most common repair is to change the spark plugs and spark plug wires (if used), or what we sometimes call a tune up. Here the price can start out at $150 for many four cylinders and range upwards of $700 for six cylinders and eight cylinders. The spark producing ignition coils are also a common item and usually average around $129 per coil (some cars have one coil per spark plug).

If you vehicle is throwing this code, schedule a diagnostic check with a mechanic immediately. Don't have a regular mechanic? No problem. Compare pricing and schedule an appointment with mechanics in your area with Openbay.

Service article written by an ASE Master Technician

If you want this service performed, Openbay can help get qualified automotive service professionals to perform the work for you.

Common Service Intervals
Synthetic Oil Change
Every 7,500 miles
Road test (Perform)
Every 7,500 miles
Drive shaft (Torque)
Every 15,000 miles
Spark plugs (Replace)
Every 60,000 miles
Air filter (Replace)
Every 30,000 miles
Coolant (Flush/replace)
Every 150,000 miles
Tire Rotation
Every 7,500 miles
Timing belt (Replace)
Every 90,000 miles
Brake fluid (Flush/replace)
Every 30,000 miles
Automatic transmission fluid (Change)
Every 60,000 miles

Book service through Openbay for:

Repair quotes from verified shops only

Seamless booking

Cash rewards

Vehicle maintenance tracker