4 Signs Your 2015-2019 GMC Sierra 2500HD Needs Ignition and Engine Management Work

Most ignition and engine management problems announce themselves well before they strand anybody. On a 2015-2019 Sierra 2500HD, these are the ones worth acting on.

1. A check engine light that flashes under load, which means raw fuel is going into the converter

This is the symptom people put off longest and regret most. Start by looking at spark plugs.

2. Fuel economy that drifts down a mile or two per gallon over a few months

By the time this is obvious you are generally replacing more than one part. Start by looking at camshaft position sensors.

3. A rough idle that smooths out above 2,000 rpm

This is the symptom people put off longest and regret most. Start by looking at crankshaft position sensors.

4. A misfire code that follows the coil when you swap it to another cylinder

This one is usually early, which is good news, because it is cheap to fix early. Start by looking at camshaft position sensors.

What to Do Next

Iridium plugs on most modern GM engines are a 90,000 to 100,000 mile item. Coils are replaced on failure, not on a schedule.

The same nameplate can have three different engines in one model year. VIN is the only reliable way to get the right plug.

Ordering is easiest if you have the VIN in front of you. Head to our GMC OEM parts catalog to shop by vehicle, or search for Sierra 2500HD spark plugs to go straight to a part.