2021 GMC SIERRA 1500 Complaints

code P1098. Engine light comes on, power is reduced, coolant fan runs on high. Temp gauge fluctuates. This last for 20 minutes or so. The engine then returns to normal. After a few days the engine trouble light goes off. This happens every several weeks. Parts are backlogged and I understand this is a common problem with this engine. I have 64000 on it.

While driving vehicle started running rough and exhaust was white from tail pipes, could not accelerate and warning lights were flashing. Limped to dealership and diagnosed with a bent rod and had to tear both sides of engine apart and replace heads on both sides due to bulletin for Gmail at 7500 miles. Why is this vehicle not part of the recall to protect my investment?

While the vehicle is traveling at highway speeds it is misfiring and sputtering, giving the feeling of a hard shift. When the vehicle is idling, the engine is sputtering like it’s going to shut off. If the truck were to shut down, as it seems to be trying to do, this could be deadly at highest speeds or intersections. The vehicle has been at a dealer since January 2025. They claimed to have fixed it but upon paying over $1200 and picking it up from the dealer, the problem persisted. We had to take it back to the dealer within 5 minutes of picking it with zero repairs and no estimated time of repairs ever since. No warning lights appeared at all.

GM has has a known issue with a switch/sensor placed at the base of the shifter that causes the “shift to park” error message that prevents the electrical system from shutting down when the vehicle is physically in park and the engine is turned off, In fact, GM has issued a recall for several different models in which a “shift to park” error message is displayed because of the poor design; however, they continue to see the same issue occur but claim it is not a warranty issue (unless it occurs within 3 year/36,000 mile time frame. This is not an issue that can be caused by owner misuse, and I believe that GM should be held liable for repairs given that the issue is, and has been, known for several years now.

So there is recall already for the engine but I’m not part of it which is weird cause my engine has been acting weird which I’m trying to take to dealer ship but they don’t want it due to I not being in the recall list. I have the engine 6.2 LTI have an 2021 GMC Sierra Denali

The engine coolant flow control valve position sensor is faulty. I brought mt truck in to my dealership and I have been waiting for over a month to get the issue fixed because “the part is on backorder”. This issue makes my truck sound like a jet engine because it makes the truck think overheating and causes the fan to come on at full blast. After drivinf for awhile it goes into “ reduced engine power mode” which is totally unsafe because it reduces the horse power to that of a lawn mower. It takes about 30 seconds to get from 0-60, so merging onto freeways or in conditions where you need extra speed its completely useless and increases the scenario of being rear ended, immensely.

VEHICLE IS DIAGANOSED WITH A COOLANT CONTROL VALVE ISSUE. VEHICLE IS CURRENTLY AT A GM DEALER AWAITNG REPLACEMENT PART AND PART IS ON BACK ORDER FOR AN UNDERTEMINED AMOUNT OF TIME. IT IS WIDELY KNOWN THIS IS A COMMON PROBLEM WITH THIS MAKE AND YEAR MODEL OF VEHICLE. THIS MATTER PUTS AN UNDUE HARDSHIP ON ME AS A VEHICLE OWNER. WITH NO KNOWN ETA FOR THIS PART I STAND TO BE OUT OF USE OF THIS VEHICLE FOR A LONG TIME. GM NEEDS TO BE MORE ACCOUNTABLE AND ATTENTIVE TO THEIR CUSTOMERS AT A TIME LIKE THIS.

The camshaft cover in pre 2021 3.0L Duramax motors is leaking oil/def internally causing oil loss. This is something GM has noted in their TSB pages but has not issued a recall over. This is a hazard to emissions, oil consumption, and the def system. Also could result in premature engine failure.

-While driving the vehicle on the highway, abruptly lost power and RPM. Check engine light, along with multiple other warning lights lit up. When parking the truck soon after, had an associated rough idle with low RPM. The truck was then towed to GMC dealership. -Multiple fuel injectors failed, starting misfiring and caused damage to the engine. Unknown if previous injectors are available, replaced at GMC dealership. The damage resulted in recommendation to replace the engine. -Engine began misfiring while traveling at highway speeds, placing me at an increased risk of loss of control of the vehicle. -The problem was reproduced, confirmed, and inspected at a GMC dealership. -No warning lights or symptoms were present prior to accident. Incident occurred abruptly.

The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving 75 MPH, the vehicle lost automotive power. The contact pulled over onto the side of the road, and upon parking on the side of the road, the message "Shift to Neutral" was displayed. The contact shifted into neutral, and the vehicle was restarted. The vehicle was taken to a local dealer, and was diagnosed, and the contact was informed that no cause for the failure was found. The vehicle was not repaired. The manufacturer was notified of the failure. The approximate failure mileage was 24,453.