Which parts fail
Components named in complaints (fuel pump, injectors, fuel tank, hybrid and EV propulsion).
Mileage when the problem started
Owner reports
Selected complaints filed with NHTSA by 2005 Isuzu Ascender owners, lightly cleaned up (personal details are redacted by NHTSA).
My 2005 isuszu Ascender had ; still has a problem associated with the fuel line and pump. I had about 75,000 miles on the car. We had been driving about 900 miles and my water pump went out, so we stopped in a Goodyear/ Firestone shop in rural mo. I had the water pump repaired. Fifteen minutes after the repair was done I stopped to refuel the car. After the pump shut off and I turned on the vehicle, my fuel gage read empty and was beeping on "e" as we drove out of gas station. After driving about 20 miles it registered as full. This continued for several fill ups. We drive far distances here in the midwest, I needed to know how much gas is in my tank at all times. I had fuel pump replaced, but now engine light stays on. My mechanic says that I need to have a pressure test at an Isuzu service center there is a leak of some type, related to my fuel line. …
I have been having issues with my gas gauge for about 3 weeks...at first I would fill up the tank or at least think it was full as the gauge would move all the way over to full then after I would stop pumping and turn on the car the gauge would go down to 3/4 tank and fluctuate back and forth between 3/4 and full over several days. Then yesterday I went and filled up and decided to not use the gauge as a measuring system and instead just let the pump go until it clicked off as it does when tank is full so I did this and the gauge went up to full then bounced back to empty and now my fuel low light is on and I cannot get any range reading on mileage for gas or anything. Also it should be noted that about that same 3 weeks ago my speedometer stopped working briefly starting off at 65 MPH at rest then it gradually made its way back down to zero at rest and has since seemed to be OK.
Tl* the contact owns a 2005 Isuzu Ascender. The contact stated that the fuel gauge, speedometer and oil gauge were all providing erratic readings. After refueling the fuel tank, the fuel gauge would provide an erroneous reading of zero. The oil gauge pressure would move back and forth when the accelerator pedal was depressed. The vehicle was taken to a local mechanic for diagnosis and they stated that the fuel pump, sensor and the lever needed to be replaced. The manufacturer was notified and advised the contact to call general motors because the parts were manufactured by general motors. The contact notified general motors but was referred back to the manufacturer of the vehicle. The vehicle was not repaired. The failure mileage was 90,000.
The first time I realized my gas gauge wasn't working, I was sitting at a traffic light. The gas hand read half full. I made the turn at the intersection and the car stopped running. At this point, I had no control over the steering wheel or anything. Traffic was heavy so I wrestled with the steering wheel to coast to the side of the road. Since then, other gauges in the instrument panel have stopped working. Also, my headlights work on bright only. I had the low beams changed and they still don't work. There seems to be a serious electrical issue with this vehicle. With the number of reports, there should be a recall to address these issues.
After checking on line, it appears that there are multiple owners of the Isuzu Ascender who have experienced failure of their fuel sending units. When I called my dealer to ask about it, he mentioned that the part is faulty and it would need to be repaired at a guess of $500. This part going bad on a customer while driving May cause an accident as the owner does not know how much fuel is left. At the same time, this trips the check engine light which May result in many stopping and calling for a tow. This part needs to be recalled due to the sheer number of complaints I have seen online.
In December of 2010 my gas gage showed empty after filling up at gas station. (14 gallons of gas had been pumped) the gage jumped up and down for two days and then showed almost full. This has happened with every fill up every week since then. I never have a correct reading on the gage. There was no warning or oddities leading up to gage not working correctly. I fill my tank every week regardless of how much gas I have in the vehicle. I see now I have been doing the best thing for my safety since the envoy is being investigated for the same issue.
The check engine light( thermostat), speedometer, fuel gauge and now the oil pressure gauge have stopped working or work sporadically and inaccurately. These problems are listed in order of failure and they started at approximately 85,000mi and the last was at 106,000 miles. If I had known this vehicle was made by GM, I would not have bought it. It will definitely be the last GM product in my household. I have had many and all but one had numerous problems. A footnote: a part of the gearshift linkage broke at approx. 95,000mi.
Tl* the contact owns a 2005 Isuzu Ascender. The contact stated that while the brakes were depressed, the engine exhibited an unusual increase in rpms of up to 3,500. The contact shifted into neutral yet the failure persisted. The contact turned off the vehicle and when restarting, the vehicle proceeded as normal. In addition, the fuel level gauge would provide erroneous fuel level readings. Neither the dealer nor the manufacturer was contacted in regards to the failure. The failure and current mileage was 85,000.
The Isuzu Ascender 2005 has had a problem with the fuel gauge, speedometer and oil gauge. All are reading erratically. Fill the tank the gauge reads that is needs gas. The oil gauge is completely as have changed out the fuel gauge inside the fuel tank for about $750 that worked for about a year and now the problem is back again. Also the check engine light is always on. The mechanic says this is an error and just resets it after checking the on board system.
2005 Isuzu Ascender-fuel gauge not working, occurred at approximately 95,000 miles. Received notice from Isuzu stating they will replace fuel level sensor if the condition occurs within 10 years of the date vehicle was originally purchased or 120,000 at no charge, which ever occurs first. My Ascender has approx. 128,000 miles, seeing that there are a lot of complaints in regard to fuel gauge Isuzu should repair it regardless of mileage.
Fuel System complaints in other Ascender years
Frequently asked questions
How common are fuel system problems on the 2005 Isuzu Ascender?
NHTSA has 24 complaints about the fuel & propulsion system of the 2005 Isuzu Ascender, 38% of the model year's 64 complaints. The component named most often is storage › fuel gauge system (3 mentions).
Is there a recall for 2005 Isuzu Ascender fuel system problems?
No. NHTSA lists no fuel & propulsion system recall for the 2005 Isuzu Ascender, though it has 1 recall for other components. If the problem is widespread, a repair may still be covered by an extended warranty or a manufacturer service bulletin — ask a dealer.
At what mileage do 2005 Isuzu Ascender fuel system problems start?
Half of the complaints with a recorded mileage happened before about 85,000 miles.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) — owner complaints through October 20, 2026, recalls and defect investigations; fuel economy from the EPA. Complaints are unverified reports and are not proof of a defect. How we rate model years.