Loss power code 43

Asked by Homer Nov 27, 2019 at 10:54 AM about the 1994 GMC Sierra 1500 C1500 SLE Standard Cab LB

Question type: Maintenance & Repair

Truck is throwing 43 code. Not the
knock sensor, new cap button EGR
solenoid,wires plugs, it's fine till third it
will shift to third then bogs down and
loses power, tries to die when stopping
unless I let of of gas and hit it again
then it stays running and does fine till
third again. Doesn't do it in overdrive
but doesn't shift to third either. Please
help. No leaks in vacuum either did the
spray test with carb cleaner

2 Answers


For kicks and giggles, check to make sure the connection on the knock sensor is tight. If it is the lets put a timing light on it and see if you are at 0 Degrees or if you are at 4 degrees retarded while the engine is up to temp. if that's the case you may have a bad knock sensor. On a cold engine check the the ohm resistance on the sensor it should be 3500 to 4000 ohms...

I'll have to find someone with a timing light to do it I know that it moves back and forth I seen a video that said it shouldn't do that idk I know I unplugged it and once I got to temp and hit third gear it started doing the same thing.

Your Answer:

GMC Sierra 1500 Experts

  • #1
  • #2
    John Saffrahn
  • #3
View All

Find great deals from top-rated dealers


Related Models For Sale

Used Ford F-150
181 Great Deals out of 12,346 listings starting at $2,197
Used Dodge RAM 1500
13 Great Deals out of 315 listings starting at $3,500
Used Toyota Tacoma
34 Great Deals out of 1,990 listings starting at $5,999
Used Chevrolet Tahoe
10 Great Deals out of 705 listings starting at $6,871
Used GMC Yukon
18 Great Deals out of 944 listings starting at $4,100
Used Chevrolet Camaro
41 Great Deals out of 921 listings starting at $8,395

Used Cars for Sale

2020 GMC Sierra 1500 For Sale
5,487 listings starting at $32,893
2019 GMC Sierra 1500 For Sale
5 Great Deals out of 2,295 listings starting at $6,635
2018 GMC Sierra 1500 For Sale
26 Great Deals out of 593 listings starting at $4,490
2017 GMC Sierra 1500 For Sale
30 Great Deals out of 645 listings starting at $16,990
2016 GMC Sierra 1500 For Sale
6 Great Deals out of 254 listings starting at $21,187

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use. Content will be removed if CarGurus becomes aware that it violates our policies.