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Reduced engine power light turns on intermittently

Tiny
JOJO222
  • MEMBER
  • 2011 BUICK REGAL
  • 0.5L
  • 4 CYL
  • AUTOMATIC
  • 140 MILES
Reduced engine power light coming on sporadically. It started last summer. Had it in at dealership twice over a two month period, they could not find the problem. Paid $80.00 each time for the diagnostic machine. It went away for a few months then it is back but now it is happening every day. Do not want to pay again only to be told they do not know. Note: car works fine, no loss of power or weird smell or leaks. Could it be a glitch?
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Tuesday, September 11th, 2018 AT 2:57 PM

19 Replies

Tiny
STEVE W.
  • MECHANIC
  • 13,452 POSTS
Welcome to 2CarPros
Common reason for a reduced power issue on a GM is a dirty throttle body or throttle position controller and sensor or the wiring harness to it. Those are in the order that is most common. Being an intermittent it would be harder to track down. Have you noticed any common times it comes on? Like under throttle or after a cold start or anything where it will "usually" come on?
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Friday, September 14th, 2018 AT 7:45 PM
Tiny
JOJO222
  • MEMBER
  • 10 POSTS
Hi Steve thanks for your response! It is coming on after one minute of driving. All my drives are within the city and under ten to fifteen minutes. (Grocery/school). Happens every time-goes off, then on, constantly. Yes, always on cold starts. Recently took hubby's outback noticed it is more peppy when accelerating than the regal. Never noticed the hesitation before. No other symptoms ie staling surges in speed rough idle. Makes sense now. Also realized I seem to be using more gas. But, can this service issue wait or will it cause damage?
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Saturday, September 15th, 2018 AT 6:32 AM
Tiny
STEVE W.
  • MECHANIC
  • 13,452 POSTS
I would get it repaired ASAP, the reason being that the excess fuel use is not going to help the catalytic converters at all, it could cause them to overheat and cost much more to repair.
Hesitation and reduced power sound like the throttle controller itself but I would think the dealer would have seen that while testing. Once you run it a while and shut off then restart does it still come on or is it only that initial cold start?
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Saturday, September 15th, 2018 AT 9:03 AM
Tiny
JOJO222
  • MEMBER
  • 10 POSTS
It happens every time. On cold starts, and restarts after five to twenty minutes. Comes on then shuts off after a few minutes only to come right back on. Will definitely take your advice and bring it in Monday morning. Wondering what your thoughts are on the problem so I do not get ripped off. Prefer not to take to dealer mine not trustworthy.
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Sunday, September 16th, 2018 AT 6:43 AM
Tiny
STEVE W.
  • MECHANIC
  • 13,452 POSTS
That should definitely show up on a scan as the light coming on will store a code that can be used as a base for diagnostics and should not be hard to reproduce if it is that constant. I try to stay out of the dealer or independent shop argument. I have seen great folks in both as well as places I would not let touch a lawnmower.
With all the short trips you drive you might want to start taking the car out once in a while and run it harder, the short trips do not get the engine warm for a long enough period of time to remove the condensation that will collect inside it. It also lets you feel the car a bit more to see if there is something wrong that does not show up in your normal driving.
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Sunday, September 16th, 2018 AT 8:08 AM
Tiny
JOJO222
  • MEMBER
  • 10 POSTS
Thank you so much for your advice. My parents always said the same re: highway driving good for the car. I will report back on the repair when done. Fingers crossed it will not break the bank!
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Sunday, September 16th, 2018 AT 8:48 AM
Tiny
STEVE W.
  • MECHANIC
  • 13,452 POSTS
It always surprises people that buying that car that Grandma had that only was driven to church on Sundays might not be a good thing. It is amazing what suddenly pops up when you take it for a more "spirited" run and discover that it has three out of balance tires, pulls to the right while braking and has a loud clunk while steering. Then you check and discover that the last oil change was more than two years ago because "It has not gone 3,000 miles yet".

Good luck and please post back what they do or do not find.
What city are you near, any good open roads nearby that you can take it on and let it stretch its legs? Or if you both drive differently, like he drives a longer route or more varied speeds maybe swap cars now and then?
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Sunday, September 16th, 2018 AT 11:16 AM
Tiny
JOJO222
  • MEMBER
  • 10 POSTS
I was given the car by my elderly mom in the spring she cannot drive anymore, she had it serviced regularly at the dealer as most seniors do. Not my style but hey it is free. We have on occasion taken to the cottage from Toronto. I have done some short highway driving twice a month or so. This issue also happened a few times on the highway. I should also mention that in addition to this issue I also had "stabilitrack" warning in June. One mechanic could not find the problem. Finally found a shop that figured out it was the break peddle assembly- very labor intensive, entire dash had to come out. Now it rattles. Feel like the regal is a lemon. Drove a Montana for eight years and had no issues. If there is anymore problems with the Buick it will have to go.
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Sunday, September 16th, 2018 AT 5:59 PM
Tiny
STEVE W.
  • MECHANIC
  • 13,452 POSTS
Did this start happening after they did the brake pedal? There are a lot of wires up there behind that dash, if one got pinched or a harness was pulled slightly it could be the cause of your problem because this is a drive by wire design, the gas pedal is fully electronic and could easily be the issue if the wiring was disturbed.
Rattles after the dash was out is a plague that happens a lot, usually because they did not put any extra sound deaden-er or made sure items were clipped in securely. A trick for that is to have someone else drive it and while it is rattling you push and prod the dash and see if you can isolate the area that is moving. Then find the seam or trim or whatever is moving, lift it or remove it and add some thin felt padding.
Oh, if this was an early build car, it was built in Germany, The Canada plant did not start production until after March of 2011. It is actually an Opel wearing GM livery by the way. Still GM but not a real domestic design.
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Sunday, September 16th, 2018 AT 7:08 PM
Tiny
JOJO222
  • MEMBER
  • 10 POSTS
It started before the stabilitrak/brake pedal thing. But only occasionally (once every other time or every third time). It is weird that it did not happen for the past three months (right after the stabilitrak thing was fixed )and all of a sudden, for the past two weeks, it is every time. I drive 500 feet and it comes on, goes off, on off.
Just heard from mechanic, he said a code was found in the history for the circuit board. Part will be $440.00 plus $220.00 labor. I am a bit concerned that this is accurate as it is a lot of cash to dish out. I have been driving for thirty years owned seven cars and never had any issues like this; just normal stuff muffler, control arm bushing etc. I have been ripped off a few times and want to make sure it is really is the circuit board.
He said it if it was dirty, a code would not have come up. Is the circuit board and throttle sensor the same thing?
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Monday, September 17th, 2018 AT 11:06 AM
Tiny
STEVE W.
  • MECHANIC
  • 13,452 POSTS
Different parts but related. There are multiple parts in the throttle and power-train control systems. A dirty throttle body may set a code or it may not, depends on where it is dirty but it sounds like he has a clue about whet the issue is. There have been multiple issues with modules and controls on the drive by wire systems, but you cannot get all the fancy things like traction control, adaptive cruise and other modern "convenience" items in the vehicle without them.
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Monday, September 17th, 2018 AT 12:12 PM
Tiny
JOJO222
  • MEMBER
  • 10 POSTS
Ah, that makes sense. I just have a funny feeling about it being the sensor. Only because a code did not come up twice at the dealership. (Nine and eleven months ago) and actually a third time for the stabilitrak thing in June, when I took it in to the guy who looked at it today.
Weird how a code came up now.
Would prefer to have the other mechanic, who fixed the stabilitrak problem, he is far but he is a wiz. I will see if he can take it tomorrow. It is an American car, speedometer is in miles not km, have no idea how fast I am going, the km numbers are so tiny! Ugg.
PS. I had the mileage incorrect, it is 109 km.
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Monday, September 17th, 2018 AT 7:34 PM
Tiny
STEVE W.
  • MECHANIC
  • 13,452 POSTS
There should be a way to switch the central drivers info center on the dash to km-h.
Yep, it says you can select the Menu on the turn signal lever. Then use the up and down arrows until you find Unit. Then select Metric or US.
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Monday, September 17th, 2018 AT 8:03 PM
Tiny
JOJO222
  • MEMBER
  • 10 POSTS
The digital display in the center is km, it is the dial that has the needle that is in miles. Since that warning is displayed in that digital display box, I cannot tell how fast I am going.
The other mechanic who was able to fix the stabilitrak issue saw the car yesterday and he said a code did come up but not pertaining to the reduced lost power (strange I got two different answers). He suggested since there i's no loss of power, hesitation, stalling or engine light coming on to leave it until I get one of those symptoms. He had it on the diagnosis machine a few times after driving it. He also checked for codes for the dash and found nothing. At least he was honest and said better not replace parts that he is not sure of.
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Wednesday, September 19th, 2018 AT 4:44 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,536 POSTS
What has the problem with the stabilitrak? Also, I have to agree with Steve I would disconnect the battery and service the throttle body thoroughly. Here is a guide to help you see how to:

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

Please run down this guide and report back.

Cheers, Ken
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Friday, September 21st, 2018 AT 11:49 AM
Tiny
JOJO222
  • MEMBER
  • 10 POSTS
The stabilitrak was the entire brake pedal assembly.
Since I had it in at the second mechanics shop the reduced engine power has not come on. Perhaps they jiggled something. Thank you for the link I will check it out.
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Saturday, September 22nd, 2018 AT 4:41 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,536 POSTS
Please let us know.
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Saturday, September 22nd, 2018 AT 11:49 AM
Tiny
JOJO222
  • MEMBER
  • 10 POSTS
This is beyond my capabilities. Next time the reduced power comes on my hubby can do it. I will report back if this made the light go off.
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Sunday, September 23rd, 2018 AT 6:11 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,536 POSTS
When the reduced power comes on lets run the codes which will tell us what is going on. I bet its just the throttle body that needs to be cleaned which is common. Here is a guide to help you see how to fix the problem. Disconnect the battery first.

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

Please run down this guide and report back.

Cheers, Ken
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Monday, September 24th, 2018 AT 11:36 AM

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