2020 Chevrolet Silverado 2500 Fuel system Problems

On approximately January 24, 2026 my 2020 Chevrolet Silverado 2500HD equipped with the 6.6 Duramax Diesel displayed an error code (P20B9). This error code was found to be related to the diesel exhaust fluid system specifically relating to "Reductant Heater A Control Circuit/Open." On January 27, 2026, the vehicle was diagnosed at Chevrolet dealership and the following was reported "Diesel Emissions Fluid Tank Remove and Replace - P20B9 SET FOR REDUCTANT HEATER CIRCUIT...COMMANDED ON AND ZERO AMPS..CIRCUITFAILURE... DISCONNECT PUMP MODULE AND BURNED/OVERHEATED TERMINALS..PUMP MODULE AND HARNESS PART OF TANK ASSEMBLY... LABOR TIME ADDED TO PERFORM MALFUNCTION/TAMPER TEST TO CLEAR EMISSIONS MESSAGE...." I found the "burned/overheated terminals" comment to be alarming. I looked into this matter further and found a GM Service Bulletin (21-NA-006) from October 2022. This bulletin identified this issue which contained an image showing burned/overheated terminals. The identified cause within the bulletin states "This condition may be caused by a poor connection at the Emission Reduction Fluid Tank electrical connector." I believe this should upgraded to a safety recall due the the potential of this terminal connection catching fire which could be detrimental for the operator, passengers, property, and the public.

NHTSA ID

11717543

Incident

Jan 24, 2026

The contact owns a 2020 Chevrolet Silverado. The contact stated that while attempting to remote start the vehicle, the vehicle failed to start. The contact was able to manually start the vehicle however, the message "Service Emissions System - Speed Limited to 65 MPH" was displayed. The contact stated while driving approximately 25 MPH, the "Check Engine” and “Speed Limit 65 MPH" messages were displayed. The contact heard an abnormal sound like air coming from the rear of the vehicle. The contact stated there was thick black smoke coming from the exhaust pipe. The contact returned to the residence. The contact had not taken the vehicle to the dealer or independent mechanic. The vehicle was not diagnosed. The contact had used a handheld scanner and became aware that the Reductant Heater circuits 1, 2, and 3 had short-circuited. The contact checked and observed that the wiring harness located under the vehicle near the fuel tank and the Diesel Exhaust Fluid (DEF) tank had melted. The vehicle was not repaired. The contact had researched online and related the failure to Technical Service Bulletin Number: N202300791 - Service Update Diesel Exhaust Fluid System (Fuel System, Diesel). The manufacturer was informed of the failure. The failure mileage was approximately 131,000.

NHTSA ID

11640476

Incident

Jan 30, 2025

Mileage

131,000 mi

The contact owns a 2020 Chevrolet Silverado 2500. The contact stated that on several occasions while driving at various speeds, the vehicle started to lose motive power and then stalled. The contact stated that on most occasions, the vehicle was restarted after one attempt. The vehicle was taken to three different dealers on several occasions however, the failure could not be duplicated. The vehicle was then towed to a dealer where it was diagnosed that the Fuel Pump Driver Module needed to be replaced. The vehicle was not repaired. The manufacturer was notified of the failure. The failure mileage was approximately 15,000.

NHTSA ID

11553922

Incident

Dec 15, 2022

Mileage

15,000 mi

My 2020 Silverado HD truck requires a replacement wiring harness and DEF tank and is basically inoperable. This is a known issue for GM and spans multiple model years.GM continued to produce throughout multiple model years knowing that owners may be stranded and unable to use these vehicles because of the defective parts. Hardships for owners would include loss of income and exposure to various dangerous conditions. The DEF tank has a heater system that can get exposed to the DEF fluid because of a poor design and poor manufacturing standards resulting in short circuit. GM will replace the wiring harness and combination tank/heater assembly under warranty. The parts are supposedly on NATIONAL BACK ORDER, yet GM continues to manufacture and ship new 2022 models with the required parts needed for repairs. GM will not provide alternate transportation. Supposedly in excess of ten thousand trucks are affected. Warm climate owners and warm temperatures may affect this issue positively. GM has no policy for a timely response to this issue. Trucks will become unsafe to operate when the electronic controls limit the truck speed to 5 mph or less. An operator may become stranded and exposed to dangerous highway conditions if stranded with this issue.

NHTSA ID

11458675

Incident

Feb 5, 2022

The DEF heater/tank shorted out. The DEF system has thrown a code 3 times in the little over a year I’ve owned the truck. This final time I was told that the tank needs to be replaced. The truck has now been in the shop for 2 months and there is still no ship date on the replacement tank. The tanks are on a national back order. From what I understand there are about 9,000 people waiting for this DEF tank countrywide. I now have a $60k work truck that I am paying for but cannot use with no reasonable end in sight.

NHTSA ID

11458547

Incident

Jan 24, 2022

Service DEF message in truck that will soon result in reduced speed. Local and purchasing dealers both stated a new DEF tank is needed. A tank is not available and is on back order.

NHTSA ID

11457303

Incident

Mar 12, 2022

DEF tank heater short causes wiring harness to melt and fault on diesel trucks, enabling limp mode. Limp mode is dangerous when hauling trailers over long distances. Faulty part is on 6 month backorder. No reparations from GM.

NHTSA ID

11456577

Incident

Mar 14, 2022

The contact owns a 2020 Chevrolet Silverado 2500 HD. The contact stated that while driving at 50 MPH, a warning alarm engaged and advised that there was an emission system issue and the vehicle needed to be serviced within 160 miles. The transmission warning light illuminated. The contact stated that she parked at some point to run an errand and upon restarting the vehicle, a death issue system alarm engaged indicating that the vehicle needed to be repaired within 90 miles. The vehicle was taken to the local dealer where the failure was diagnosed as a dead issue and one of the pins on the wiring harness had burnt and was starting to melt. The local dealer informed the contact that the death tank and wiring harness needed to be replaced; however, the parts for the repair were not available the vehicle was not drivable. The vehicle was not repaired. The manufacturer was notified of the failure and advised the contact the parts for the repair were not available. The vehicle was not repaired. The failure mileage was approximately 20,000.

NHTSA ID

11451528

Incident

Jan 22, 2022

Mileage

20,000 mi

MY VEHICLE IS LESS THAN 1 YEAR OLD WITH ABOUT 11500 MILES. MY SERVICE EXAUST SYSTEM WARNING LIGHT ILLUMINATED AND PROVIDED A WARNING THAT MY SPEED WOULD BE REDUCED IN A SET AMOUNT OF MILES. AFTER ADDING ADDITIONAL DEF FLUID TO DETERMINE IF THAT WAS THE ISSUE MY CAR THE CAR RETURNED AN ERROR OF SERVICE DEF SYSTEM. THIS THEN LOWERED THE AMOUNT OF DRIVING MILEAGE UNTIL MY CAR WOULD BE FORCED TO A REDUCED SPEED. THIS OCCURRED WHILE OPERATING THE VEHICLE AND MAY HAVE RESULTED IN DAMAGE TO MY VEHICLE OR OTHER MOTORIST WHEN TRAVELING ON AN EXPRESSWAY. THE DEALER EXPLAINED THAT THEY HAD OTHER CARS IN FOR THE SAME ISSUE AND IT TOOK OVER A MONTH TO GET THE PARTS IN FOR REPAIR. ADDITIONALLY GM HAS PROVIDED NO GUIDANCE OR WARNING REGARDING THE ISSUE.

NHTSA ID

11397309

Incident

Feb 3, 2021

Mileage

11,500 mi

VEHICLE IS A DIESEL HAS ABOUT 13,000 MILES ON IT ONLY. RECEIVED A WARNING ON THE DASH WHILE VEHICLE WAS IN MOTION THAT THE DEF SYSTEM HAS AN ISSUE AND TO SEE THE OWNER MANUAL. SAYS ABOUT 80 MILES UNTIL MAX SPEED WILL ONLY BE 65 MPH. TOOK TO DEALER AND STATED THAT IT IS THE DEF PUMP IN THE TANK. THE PART IS ALMOST IMPOSSIBLE TO GET RIGHT NOW BECAUSE IT HAS BEEN FAULTY ON SO MANY OF THESE VEHICLES AND HAS NEEDED REPLACEMENT. HAVE TO LEAVE VEHICLE AT DEALERSHIP UNTIL THEY CAN GET A PART IN OTHERWISE VEHICLE CANNOT BE DRIVEN.

NHTSA ID

11394327

Incident

Feb 1, 2021

Mileage

13,000 mi

THREE DAYS AFTER PURCHASING MY 2020 CHEVY 2500 SILVERADO, ON SEPTEMBER 28TH, 2020 AROUND 1253 I TRIED TO START MY TRUCK AND IT WOULDN'T START. THE TRUCK TURNED OVER BUT SEEMED LIKE IT WASN'T GETTING FUEL. I THEN RECEIVED A DIAGNOSTIC ALERT. AFTER CHANGING THE RELAY THE TRUCK RAN FINE. I THEN SCHEDULED TO TAKE IT IN TO THE DEALER ON OCTOBER 5,2020 TO HAVE A DIAGNOSTIC DONE ON THE TRUCK AND THEY FOUND NOTHING. THE VERY NEXT DAY IT DID THE SAME THING ON OCTOBER 6TH, 2020. I THEN SCHEDULED TO HAVE IT TAKEN IN AGAIN AND FOUND OUT THAT THE FUEL CONTROL MODULE ON SEVERAL OTHER GM VEHICLES WHERE FAULTY ON NEW VEHICLES. I HAD TO CANCEL MY SECOND APPOINTMENT DUE TO THE DEALER WOULDN'T PROVIDE ME WITH A LOANER CAR WHILE THEY WORKED ON MY TRUCK. THIS VEHICLE IS UNDER WARRANTY. THEN AGAIN ON THE OCTOBER 20TH, 2020 THE VEHICLE WOULD NOT START. AFTER CHANGING OUT THE RELAY SWITCH IT SEEMED TO RESET THE SYSTEM AND STARTS AND RUNS FINE AND THE CHECK ENGINE LIGHT GOES OFF. I WORK IN EMERGENCY SERVICES AND NEED MY TRUCK TO RUN WHEN I TURN THE KEY OVER. THERE'S NO COMMON FACTOR LEADING TO THIS LACK OF TURNING OVER. AND MY DEALER IS NOT WORKING WITH ME TO COME TO A SOLUTION TO THIS PROBLEM. THIS HAS HAPPENED ON 3 OCCASIONS AT RANDOM TIMES.

NHTSA ID

11366110

Incident

Oct 22, 2020

Mileage

328 mi