Reduced power turns on when idling

Tiny
DEJUAN LYONS
  • MEMBER
  • 2004 ISUZU RODEO
  • 3.5L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 166,000 MILES
I am driving my vehicle down the road, and when I am sitting idle at a red light or somewhere after driving, the reduced power light comes on. It stays on while I am idle but when I accelerate, it goes out and stays off until I sit idle again. My check engine light is also illuminated but not blinking or anything. Do you think that the code is stored in my ECU or that I have a bad ECU since the battery was charged and terminals were changed? I am also getting a code of P0456 from the Auto parts store machine. How can I find out where a small EVAP leak is if I don't smoke or own a smoke machine?
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Tuesday, November 26th, 2019 AT 3:37 AM

23 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 42,554 POSTS
Hello,

The EVAP code will not cause the car to go into limp mode, it sounds more like the throttle actuator needs to be serviced. Here is a guide to help us fix the problem:

https://www.2carpros.com/articles/throttle-actuator-service

and

https://www.2carpros.com/articles/reduced-power-limp-mode

Please run down these guides and report back.

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Wednesday, November 27th, 2019 AT 2:48 PM
Tiny
SMA530
  • MEMBER
  • 2 POSTS
  • 2004 ISUZU RODEO
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 56,553 MILES
Both check engine and reduced power light constantly coming on, I lose power while driving and can only go about 35mph. Have had both catalytic converters checked, MAF replaced and put back, both TPS' replaced and still have the same problem. At first the same three codes would show up p1515, p1125, and p1295. Then the other day while running the car it began to shut off by itself every once and a while. Then all of a sudden it went from the same three codes to 12 codes. Disconnected battery and when lights came on 15 codes appeared, then when we did the same thing 20 codes appeared. If given a day the car will run fine for about thirty minutes then check engine light and reduced power again. What could the problem be? Could it be the wiring? Or could it be that I need a new computer? Can I get the computer checked out somewhere?
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Friday, January 8th, 2021 AT 9:24 AM (Merged)
Tiny
FIREMAN103
  • MEMBER
  • 4 POSTS
I googled the three codes for you and this is what came up. I recently had the same problem with my wifes car and we replaced the TPS and it runs just fiine. The TPS is a dealer only part which costed us 150 bucks. Hope this helps.


https://www.2carpros.com/forum/automotive_pictures/482394_1295_1.jpg



https://www.2carpros.com/forum/automotive_pictures/482394_1515_1.jpg


https://www.2carpros.com/forum/automotive_pictures/482394_1125_1.jpg

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Friday, January 8th, 2021 AT 9:24 AM (Merged)
Tiny
SMA530
  • MEMBER
  • 2 POSTS
We thought it was that too but when we replaced the TPS the car still had the same problems. If I let the car rest a few days it drives fine for a day then after that back to reduce power and check engine. It's as if the longer it rest and no one drives the longer it will go without messing up sometimes it will last 2 to 3 days. Does anyone have any other suggestions?
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Friday, January 8th, 2021 AT 9:24 AM (Merged)
Tiny
RONBOW64
  • MEMBER
  • 4 POSTS
My car is doing the same thing I need help to what is it?
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Friday, January 8th, 2021 AT 9:24 AM (Merged)
Tiny
STEVE W.
  • MECHANIC
  • 12,883 POSTS
RONBOW64 Please use this link to ask your question as a new one. It will then show up to more people Please include all of the information you can about the problem and the vehicle. Thank you. https://www.2carpros.com/questions/new
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Friday, January 8th, 2021 AT 9:24 AM (Merged)
Tiny
BEVJ1966ME
  • MEMBER
  • 2 POSTS
  • 2004 ISUZU RODEO
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 68,000 MILES
The Check Engine light and the reduced power light both come on and the car will only move about 1 mile an hour, it just inches along until I get it home. I took it to 2 mechanics who said it might be the catalytic converter but it has dual converters and they could not tell which one. I took it to a muffler shop and they said that the dealer had put a chip in and their diagnostic equipment could not read it to determine the problem. I took it to the Izusu dealer and they kept it the first time about 6 days and said they could not find out anything becasue the lights would not come on for them. I brought it home and drove it from March to this month May 5th when it did it again and the dealer had it towed to the dealership on May 5th. When they finally looked at it on May 8th it was not doing it, so they still have it there. Any suggestions?
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Friday, January 8th, 2021 AT 9:24 AM (Merged)
Tiny
RACEFAN966
  • MECHANIC
  • 5,029 POSTS
Ok you need to know what the codes are that are turning on the engine light. So call around to your local parts stores and find one that will do a free scan and have it scanned and write down the codes and then have them clear them. Get back to me with the codes and we will go from there.
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Friday, January 8th, 2021 AT 9:24 AM (Merged)
Tiny
BEVJ1966ME
  • MEMBER
  • 2 POSTS
The Rodeo is still with the Dealer's service department. If I get it back and it is not fixed then I will follow your advice.
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Friday, January 8th, 2021 AT 9:24 AM (Merged)
Tiny
RACEFAN966
  • MECHANIC
  • 5,029 POSTS
OK let me know how it goes. Thanks
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Friday, January 8th, 2021 AT 9:24 AM (Merged)
Tiny
PCOTTONE
  • MEMBER
  • 2 POSTS
My rodeo is doing the same thing and has been for 5 years. No one seems to know. I have had diagnostic testing done and expensive repairs because of this and still having issues. It is currently parked because I am scared to death it will konk out on the highway. I does not happen all the time but when it does it is non stop. Need help please if anyone knows, It sounds like a sensor to me and it is not the engine despite the light on.
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Friday, January 8th, 2021 AT 9:24 AM (Merged)
Tiny
DEJUAN LYONS
  • MEMBER
  • 4 POSTS
  • 2004 ISUZU RODEO
  • 3.5L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 165,000 MILES
One day I was driving my vehicle taking a friend to work. It began to jerk all of a sudden and the Reduced Power light illuminated on the dash. I began to lose power. I went to my local mechanic that I trust and they stated that it was the fuel pump. Not knowing that I have 2 fuel pressure pumps in my vehicle, I got the one in the tank done. I was told later on that it was the High Fuel Pressure Pump. Could this be the cause of my Reduce power light staying illuminated? And what could the other causes of code p1239 mean for my vehicle listed above?
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Friday, January 8th, 2021 AT 9:24 AM (Merged)
Tiny
SCGRANTURISMO
  • MECHANIC
  • 4,897 POSTS
Hello,

I have included for you the factory diagnostic troubleshooting flowchart for Direct Trouble Code(DTC) P1239 for your vehicle. Please go through this flowchart and get back to us with what you find out.

Thanks,
Alex
2CarPros
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Friday, January 8th, 2021 AT 9:24 AM (Merged)
Tiny
MOHD40
  • MEMBER
  • 3 POSTS
  • 2004 ISUZU RODEO
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 80,000 MILES
Check engine keeps lighten and go off from time to time, if it is on the speed cruise does not start and the reduced power lights on long stops or when you put gear on D while care is stopped.
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Friday, January 8th, 2021 AT 9:25 AM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
https://www.2carpros.com/articles/service-engine-soon-or-check-engine-light-on-or-flashing

Have the computer scanned for code/s-you have a problem within the engine management system that caused the CEL to turn on-This is your starting point of diagnosis,finding out what's going on.
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Friday, January 8th, 2021 AT 9:25 AM (Merged)
Tiny
MOHD40
  • MEMBER
  • 3 POSTS
The computer scan code is p1239, I still have the problem and I have tried almost every thing but now the check engine is almost on all the time and when ever I stop reduced power lights as well, I have noticed that when the car fuel level is low (fuel light is on) check engine light goes off for some time.
Any body have anu idea?
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Friday, January 8th, 2021 AT 9:25 AM (Merged)
Tiny
MIKEANDIKE
  • MEMBER
  • 4 POSTS
  • 2004 ISUZU RODEO
  • 3.5L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 7,900 MILES
When I clear the code it will accelerate but not running well. The code is not in my book can you tell me what the means? This is the code P1239.
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Friday, January 8th, 2021 AT 9:25 AM (Merged)
Tiny
WRENCHTECH
  • MECHANIC
  • 20,757 POSTS
Your car has both a high pressure and low pressure fuel supply systems. The low pressure supply pump in the tank and a high pressure pump on the engine that brings the pressure up over 1500PSI. The code indicates the pressure on the high side is incorrect. This is a very dangerous system to work on and I suggest you have a competent local mechanic look at it.
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Friday, January 8th, 2021 AT 9:25 AM (Merged)
Tiny
MIKEANDIKE
  • MEMBER
  • 4 POSTS
I replaced that pump and no I am not a mechanic. I am an auto body mechanic and I work on the lighter side of mechanical.
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Friday, January 8th, 2021 AT 9:25 AM (Merged)
Tiny
WRENCHTECH
  • MECHANIC
  • 20,757 POSTS
That kind of pressure can really hurt you if you do not know how to unload it.
You could have an electrical issue associated with the pump solenoid circuit.
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Friday, January 8th, 2021 AT 9:25 AM (Merged)

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