2008 GMC Yukon Reduced engine

ST12

MEMBER
2008 GMC YUKON

Engine Performance problem
2008 GMC Yukon V8 Two Wheel Drive Automatic

I would like to ask merlin2021 a question
Dear Merlin,
My 2008 GMC Yukon has had reduced engine power 5 times. Each time they tell me it is fixed. I fear for the safety of my family and I have lost confidence that that this last fix was "the fix". The problem is intermittent and sudden. It runs fine between each fix and currently it is running fine.
My question:
What are the possible causes of reduced engine power?
So far they:
1.) Found code P2138 then found bulletin 070604019 to check body connector necessary to clean connection and repair leak from L frt sunroof drain hose
2.)Caused by possible poor connection at C200 causing code P2138 Corrected by N6608: (P2138) wiring and/or connector emissions system repair or replace perform tect II diag, code P2138 set, found bulletin 070604019 & PIP3738 3B, water test vehicle, R&R upper dash/instrument panel trim & defroster grille & inspect, secure C200, clear codes and road test
3.) Caused by 2138 stored APP Sensor 1-2 connection Corrected by N6608: (WG) (P2138) wiring and/or connector emissions system repair or replace. Preformed bulletin 07-06-04-019A and PIP 3783B, checked connectors C109, C205 No corrosion seen all terminals tight, no signs of water introsion verified all conn properly seated and locked cleared DTC.
4.)Caused by: No current DTC's stored, APP sensor data within parameters, P213B history Corrected by J6360: (PL) (11EC4) module, PCM/VCM replace. Installed 12612384: module (03670-pckt) 12612 Qty:1 Check all connectors and APP circuit, intermittent ECM malfunction, replace ECM, peformed programming. (Please note: the battery was dead when I brought it in because we left the lights on waiting for AAA to tow us to the shop. They replaced the battery before they did the other work.)
5.)Caused by: DTC 2138 APP sensor 1-2 correlation, Corrected by J5350 (WG) (P2138) pedal, accelerator replace Installed 25832864: pedal (03451-CT) diagnosred intermittent APP sensor failure, replace accelerator pedal position sensor (pedal assy) clear DTC, test drive 39 miles, no codes reset
So is there anything else that could go wrong?
Thank you for all of your time and expertise.
st12

1 Reply

MERLIN2021

MECHANIC
17,250 POSTS

Well. This applies to the connector for the Instrument Panel, it may have damaged the IP itself. Any gauges acting up? Here's the actual Bulliten on the issue:
Page 1 of 2
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Intermittent MIL/SES, DTC P2138 with Reduced Engine Power (Repair Instrument Panel (IP) to Body Harness Connector)
TECHNICAL SERVICE BULLETIN
Reference Number(s): 07-06-04-019A, � Date of Issue: � November 06, 2008 Affected Model(s): 2005-2008 GM Passenger Cars and Light Duty Trucks (Including Saturn); 2005-2008 HUMMER H2; 2006-2008 HUMMER H3; 2005-2008 Saab 9-7X This Bulletin is being revised to add additional diagnostic service information. Please discard Corporate Bulletin Number 07-06-04-019 (Section 06 - Engine/Propulsion System) Supercedes:
Related Ref Number(s): 07-06-04-019, 07-06-04-019A
ARTICLE BEGINNING
CONDITION
Some customers may comment on an intermittent MIL/SES light Illuminated with a message center or an indicator that displays Reduced Engine Power. DTC P2138 - Accelerator Pedal Position (APP) Sensor 1-2 Correlation may be set. The voltage difference between APP sensor 1 and APP sensor 2 exceeds a predetermined value for more than a brief period. Refer to DTC P2138 in SI for further diagnostics.
CAUSE
On some vehicles, the IP to body harness connector, which carries the APP signal to the ECM/PCM, is located in the left hand kick panel area or inside the IP. Water intrusion into these areas could cause an electrical short in the APP circuits setting a P2138 code.
CORRECTION
NOTE: Make sure that no add-on/aftermarket equipment is electrically connected to the APP signals or to the other ECM/PCM five volt reference or return lines. These can generate false P2138 and/or other ETC System DTCs. If there are other engine DTCs besides P2138, such as MAP sensor faults (i.E. P0107, P0108), resolve these first before attempting to diagnose P2138 DTCs.
IMPORTANT: Refer to DTC P2138 in SI to confirm that the ETC pedal is operating correctly.
Locate the IP to body harness connector, which may be located in and around the left hand kick panel area or inside the IP. Check to see if there is a water leak into the area and repair as necessary. Use a water hose to determine the source of a water leak and effectiveness of repair. Some examples of potential water leaks are: A-pillar seals, sunroof drain lines (if so equipped) and windshield/cowl sealing. Finally, repair or replace the IP to body harness connector, making sure no corrosion or
6/4/2009 .
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debris is left on or between the terminals.
WARRANTY INFORMATION (EXCLUDING SAAB U.S. MODELS)
For vehicles repaired under warranty, use:
Warranty Information (excluding Saab U.S. Models) Labor Operation Description Labor Time N6608 Wiring And/Or Connector-Emissions System - Repair Or Replace Use Published Labor Operation Time
WARRANTY INFORMATION (SAAB U.S. MODELS)
For vehicles repaired under warranty, use:
Warranty Information (Saab U.S. Models) Labor Operation Description Wiring And/Or Connector-Emissions System - Repair Or Replace Failed Object 3713501 Fault/Reason Code 37135 61 0 01 01 (Replace) 05 (Repair) Location Code Repair/Action Code Warranty Type
Labor Time
Use Published Labor Operation Time
6/4/2009 .