P1174 code

Hi,

The code indicates an issue with cylinder fuel trim balance. The code indicates there is a lean / rich fuel mixture between cylinders. Here is the manufacturer's definition of the issue.

DTC Descriptors

DTC P1174
- Fuel Trim Cylinder Balance

DTC P1175
- Fuel Trim Cylinder Balance

Circuit/System Description

The Fuel Trim Cylinder Balance diagnostic detects a rich or lean cylinder to cylinder air/fuel ratio imbalance in each bank. The diagnostic monitors the pre-catalyst heated oxygen sensor (HO2S) signal's frequency and amplitude characteristics by calculating an accumulated voltage over a predetermined sample period. An imbalance is indicated when multiple samples of the accumulated voltage are consistently higher than the desired value.

What that simply means is there is more fuel being used by one or more cylinders than the others. In this case, it is related to bank 1. Here are the most common causes of this type of problem:

1) Clogged fuel injector
2) Ignition problem as far as spark or timing
3) A bad oxygen sensor
4) An internal engine issue.

__________________________

I also want to note there is a technical service bulletin (TSB) related to this code from GM. Here is the TSB. Take a look through it. It indicates specific things to check for.

__________________________

2008 Chevy Truck Silverado 1500 2WD V6-4.3L
SES Light with Fuel Trim and or Oxygen Sensor Codes
Vehicle ALL Diagnostic Trouble Codes ( DTC ) Technical Service Bulletins SES Light with Fuel Trim and or Oxygen Sensor Codes
SES LIGHT WITH FUEL TRIM AND OR OXYGEN SENSOR CODES

#PIP4925B: SES Light with Fuel Trim and or Oxygen Sensor Codes - (Dec 3, 2018)
Subject: SES Light with Fuel Trim and or Oxygen Sensor Codes

Pic 1

Supersession Statement
This PI was superseded to update Model Years and add diagnostic recommendations. Please discard all copies of PIP4925A

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern
A customer may comment the vehicle has an SES light on. Initial diagnosis may display any of these fuel trim and/or O2 sensor related codes, P0101, P0137, P0138, P0140, P0141,P0157, P0158, P0160, P0161, P0171, P0174, P0420, P0430, P1174, P1175, P2096, P2097, P2098, P2099, P2177, P2178, P2179, P2180, P2187, P2188, P2189, P2190. P2270, P2271, P2272, P2273.

Recommendation/Instructions
If normal SI diagnostics does not lead to a resolution and an intake vacuum leak or an exhaust leak is suspected, the use of the J41413-200 Evaporative System Tester smoke machine or the J-41416 ultrasonic leak tester, or possibly using soapy water and low pressure air into the tailpipe may be useful to find the leak.

Note: : All of these tests are much more effective if the throttle body is covered/sealed. For an intake leak the smoke can be introduce into the brake booster hose or the oil dipstick tube.Soapy water can be sprayed near the gasket and seams and all vacuum nipples.

For an exhaust leak the hose into the tailpipe, with smoke or air, sealed with shop towels proves to be effective.

Then soapy water would be sprayed around seal, seems and bosses.

Ultrasonic leak detector may also find leaks in this way.

These methods are very good for finding small leaks around the O2 sensor embossments and slight cracks in an intake plenum or gasket.

This process was also recommended in the 10207.07D - July 2007 Emerging Issues training seminar.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.

_________________________________

The TSB seems to indicate checking for vacuum leaks as well as possible exhaust leaks. The exhaust leak, in this case, will most likely be at the exhaust manifold. Often times they make a ticking sound or simply they sound like a bad muffler. So check for that. Here is a link that will explain how to check for engine vacuum leaks:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Please let me know if this helps or what you find. If you have additional questions, let me know.

Take care,
Joe