Q: P0300 code, misfiring on a '06 Hmamer H3

asked by on May 17, 2016

06 Hammer H3, 87,000 miles, inline 5 engine. Got the P0300, multiple misifres. I've changed the sparkplug, coil pack, VVT solenoid, cleaned the throttle body and MAF. I don't know what else to do. Any ideas?

Those things are notorious for having fuel injection problems. GM made them with cheap plastic and the fuel injection parts, so when they get to be older, after 10 years old, the plastic cracks, leaks, and gets multiple misfires. That’s a typical problem with that.

It can be hard to diagnose the P0300 code yourself. It can easily be the injection system and that is a very complex system. You don’t want to take the whole engine apart yourself, which you’d have to do to get to the injection system. My recommendation would be to have a professional technician, diagnose Check Engine Light for you and make the necessary repairs.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Code P2135-Error codes read - Throttle position sensor circuit range/performance. Is this something a regular mechanic can report

Hi there. The P2135 is one of most misdiagnosed trouble codes for mechanics. This particular trouble code indicates that the Power Control Module (PCM) has detected an erroneous reading regarding the voltages transmitted by throttle position sensor A or B,...

Car spits an sputters like it's misfiring if I accelerate too fast. But does fine any other time

Hey there. The first thing I would check would be the fuel pressure. But there are several possible causes for this condition. There could be a vacuum leak, the engine may need a tune up, or any number of other...

Charging system failure.

This may suggest a failing voltage regulator. The voltage regulator is a unit that regulates the charging of the battery by the alternator. When the voltage regulator is not working properly, this may result in the alternator allowing too much...

Related articles

What Causes Spark Plugs to Wear Out?
Without operational spark plugs, your engine won’t run. If even just one plug were to fail, the change in functionality would...
How to Check Spark Plug Wires
Car engines that have a distributor or remote coil pack have spark plug wires that transfer the spark from the coil to the spark plug.
P0300 OBD-II Trouble Code: Random/Multiple Cylinder Misfire Detected
P0300 code definition Random/multiple cylinder misfire detected What the P0300 code means Most vehicles will have 4-6 cylinders. Each cylinder will fire...