GMC Yukon 2000–2006

Manufacturer communication2001–2006 GMC YUKON DENALI ・ 2024-03-19

Internal Coolant Leak from Cylinder Head Location

1. 1Fault

   • Leak
   • Some vehicles may experience a gradual coolant loss over time.
   ↓→

2. 2Finding the cause

   Possible causes

   • A very low percentage of cylinder heads manufactured with an embossed Castech logo may develop a porosity crack in a very specific area.

   Steps to confirm (in the document’s order)

   1. Check whether the head is a Castech casting by looking for the casting logo on top of the intake port, under the rocker arm support rail and in the spring deck cavity portion of the cylinder head.
   2. If the head is a Castech casting, inspect the area around the five oil drain holes for witness marks indicating coolant seepage over time.
   3. The crack can be in any of the five cylinder head oil drains and shows as a clean or shiny area on an otherwise stained surface.
   4. Pressurizing the cooling system at this time may reveal coolant, air, or a combination weeping in the described area.
   ↓→

3. 3Correction

   Repair

   • If inspection reveals evidence of coolant witness marks, replace the entire cylinder head assembly.

   Caution

   • If the cylinder heads are not a Castech casting, follow normal diagnostic procedures in SI to determine the cause of the coolant loss.
   • If no evidence of coolant loss is found on inspection of Castech casting cylinder heads, follow normal diagnostic procedures in SI to determine the cause of the coolant loss.

Manufacturer communication2002–2006 GMC YUKON DENALI ・ 2019-04-08

Service Engine Soon Lamp at Low Mileage

1. 1Fault

   • Warning light
   • Check engine / Service Engine Soon
   • P0420
   • P0430
   • An SES light may come on on low mileage vehicles or vehicles that recently had the catalytic converter replaced, with DTCs P0420 and/or P0430 stored.
   ↓→

2. 2Finding the cause

   • Catalytic Converter: failed

   Possible causes

   • On a new vehicle, catalytic converter efficiency DTCs P0420 and P0430 are disabled for the first hour of engine run time to allow break-in of the catalytic converter.
   • If the engine run time is less than one hour, the battery may have been disconnected, or another vehicle power loss event may have occurred, during vehicle manufacturing.
   • If the DTCs set shortly after the catalytic converter is replaced, it may be because the engine run time restrictions are no longer in place since the vehicle is no longer new.
   • As a result, the catalytic converter may not have completed a thorough break-in cycle after replacement, possibly resulting in a false DTC P0420 and/or P0430.

   Steps to confirm (in the document’s order)

   1. On a new/low mileage vehicle with these DTCs, use the Tech 2 to verify engine run time on the Engine Hour Meter in the IPC Data Display/Data 1 List.
   2. Finally, restart the engine and operate the vehicle at the conditions for running the DTC P0420/430 tests, and make sure the vehicle passes them.
   ↓→

3. 3Correction

   Repair

   1. Clear the DTCs and perform the drive cycle given in the document.
   2. Drive cycle step: drive the vehicle at sustained highway speed for 25 to 30 minutes.
   3. Drive cycle step: restart the engine and resume highway speed for an additional 10 to 15 minutes.
   4. If the diagnostics do not pass, perform SI diagnostics and repair as necessary.

Manufacturer communication2002–2006 GMC YUKON DENALI ・ 2023-05-06(3 earlier editions of this document folded here)

Diagnostic tip: valve, lifter or camshaft issue

1. 1Fault

   • Misfire or rough idle
   • Noise
   • Warning light
   • P0300
   • P0301
   • P0302
   • P0303
   • P0304
   • P0305
   • Misfire, chirp, squeak, squeal or tick noise, or MIL illuminated.
   • DTCs P0300 (engine misfire detected) and P0301 through P0308 (misfire detected on cylinders 1 through 8) are listed.
   ↓→

2. 2Finding the cause

   Possible causes

   • Possible causes: worn camshaft lobe and/or lifter roller, a sticking valve, valve leakage, a broken valve spring, or a collapsed AFM lifter.

   Steps to confirm (in the document’s order)

   1. A verified noise is not eliminated by canceling fuel injectors and occurs at camshaft speed (half of crankshaft speed).
   2. If applying pressure to the valve side of the rocker changes the noise, a lifter and/or cam lobe concern on that cylinder is most likely.
   3. Disconnect the coils and injectors on one bank, run the engine with that valve cover removed, back off the rocker arm a couple of turns and listen for a change in the noise.
   4. Measure cam lobe lift at the pushrod side of the rocker arm and compare with other rockers on the same bank; the misfiring or ticking cylinder should have clearly less lift.
   5. A good indicator of a sticking valve is misfires that keep counting on an aggressive deceleration with engine braking.

   1 more points
   ↓→

3. 3Correction

   Repair

   • If a worn camshaft lobe or lifter roller is found, replace the camshaft and all lifters, and the plastic lifter guide for the affected lifter.

   Caution

   • A damaged cam lobe is easy to overlook through the lifter bores, and unworn lifter rollers do not mean the cam lobes are okay; inspect both carefully.

Owner complaint2002 GMC YUKON DENALI ・ 2003-06-11

Intermittent noise from right rear of vehicle; returned after exhaust system change

1. 1Fault

   • Noise
   ↓→

2. 2Finding the cause

   Not stated

   ↓→

3. 3Correction

   • Exhaust System: replaced (says it held for a while)

Manufacturer communication2000–2006 GMC YUKON DENALI ・ 2024-02-29(2 earlier editions of this document folded here)

Oil Cooler, Oil Cooler Lines, and Oil Tank Replacement Service Information

1. 1Fault

   Not stated

   ↓→

2. 2Finding the cause

   Possible causes

   • Debris from a damaged rod or main bearing is sent directly through the oil galleries and the components in the lubrication circuit.
   ↓→

3. 3Correction

   • Oil Cooler: replaced
   • Oil Cooler Line: replaced
   • Oil Tank: replaced

   Repair

   1. Whenever an engine assembly is replaced for a connecting rod or crankshaft main bearing failure, also replace the oil cooler, oil cooler lines, oil tank and turbocharger, if equipped.
   2. If the oil cooler is part of the radiator assembly, the radiator must be replaced along with the other required components.

   Caution

   • Reinstalling an oil cooler or cooler line from an engine with bearing failure debris may carry remaining debris into the new service engine.
   • Some service engines come with the oil cooler and/or oil cooler lines already attached; those need not be replaced.
   • Not every engine with bearing damage requires the oil cooler, lines or oil tank, or even the engine, to be replaced.

Manufacturer communication2000–2006 GMC YUKON DENALI ・ 2024-02-02

Piston Installation Procedure

1. 1Fault

   Not stated

   ↓→

2. 2Finding the cause

   Steps to confirm (in the document’s order)

   • Refer to the Engine Mechanical Specification in SI for the correct bore and piston specification.
   ↓→

3. 3Correction

   Repair

   1. When installing a piston into a cylinder, use a ring compressor sleeve or equivalent for best results.
   2. Choose a sleeve with a smooth radius that tapers down to the specific bore size.
   3. Select a size only slightly bigger than the piston diameter and not larger than the cylinder bore diameter.

   Caution

   • If a sleeve is unavailable in the needed size, a universal ring compressor will work but is more difficult to use.

Manufacturer communication2001–2005 GMC YUKON DENALI ・ 2023-12-11

Expanded Availability for Remanufactured Electronic Control Modules

1. 1Fault

   Not stated

   ↓→

2. 2Finding the cause

   Not stated

   ↓→

3. 3Correction

   Expanded Availability for Remanufacture and Return (R&R) Electronic Control Modules

Manufacturer communication2000–2006 GMC YUKON DENALI ・ 2023-09-26

Normal Transmission Shift and Throttle Response Delay

1. 1Fault

   • Loss of engine power, no acceleration
   • A sag or hesitation may be noticed when coasting at low speeds of less than 24 km/h (15 mph) with a closed throttle and then aggressively applying the throttle.
   • With an automatic transmission, after a hard complete stop with a closed throttle immediately followed by an aggressive throttle opening, the downshifts may not be completed by the time the throttle is opened.
   • A sag or hesitation may also be noticed while cruising at highway speeds and then aggressively increasing the throttle, forcing a down-shift.
   ↓→

2. 2Finding the cause

   Possible causes

   • In this maneuver the throttle blade is opened slowly for up to 0.7 seconds, even though the accelerator is applied aggressively, to help minimize driveline lash and clunking.
   • As a result, approximately 0.5 seconds of zero torque may be commanded to allow the shift to first gear to occur.
   ↓→

3. 3Correction

   Caution

   • All of these conditions are a result of Torque Management and should be considered normal; no repairs should be attempted.

Manufacturer communication2000–2006 GMC YUKON DENALI ・ 2023-09-15

Engine Component Wear Service Guidelines

1. 1Fault

   • Some technicians may be replacing engines instead of repairing them and replacing worn components as needed.
   ↓→

2. 2Finding the cause

   Possible causes

   • The wear may be caused by the vehicle duty cycle, dust in the operating environment and local fuel quality.

   Steps to confirm (in the document’s order)

   1. Cylinder wall scratch: if a pick or fingernail cannot catch on it, the cylinder bore/engine block does not require replacement.
   2. With a scored piston, inspect for broken and/or stuck rings, and inspect the ring lands and cylinder wall for damage.
   3. When bearing failure is suspected, remove the oil filter and inspect it for excessive debris and damaged pleats.
   4. Minimal amounts of metal particles on the oil filter pleats should not pose a concern.
   5. Excessive metal particles or damaged filter pleats mean unfiltered oil with bearing debris may have been pumped into the oil galleries throughout the engine.
   ↓→

3. 3Correction

   Repair

   1. Minor scratching/scoring on camshaft lobes and/or camshaft bearing journals: the scored components can be replaced without replacing the engine assembly.
   2. Minor scratching/scoring on connecting rod bearings: the scored components can be replaced without replacing the engine assembly.
   3. A slightly scored piston can be replaced without replacing the engine assembly.

   Caution

   • If inspection reveals cylinder wall damage (excessive scoring or out-of-round), an engine replacement may be required.

Manufacturer communication2000–2006 GMC YUKON DENALI ・ 2023-04-12(4 earlier editions of this document folded here)

ACDelco Spin-On Oil Filter Torque Specification Notification

1. 1Fault

   • Leak
   • An oil leak from underneath the front of the vehicle after an earlier oil service; the leak can take several thousand miles to appear.
   ↓→

2. 2Finding the cause

   Possible causes

   • The oil may be leaking from between the oil filter gasket and the mounting surface.

   Steps to confirm (in the document’s order)

   • The filter may be very easy to remove, sometimes by hand.
   ↓→

3. 3Correction

   Repair

   1. Lubricate the new oil filter gasket with clean engine oil.
   2. Install the oil filter 1 full turn after the gasket contacts the sealing surface on the filter mounting flange.

Manufacturer communication2000–2006 GMC YUKON DENALI ・ 2023-01-06

EVAP Leak Diagnostic Service Bulletin (DTCs P0442/P0455)

1. 1Fault

   • Leak
   • Warning light
   • P0442
   • P0455
   • The MIL is illuminated, and DTC P0442 (EVAP small leak detected) and/or P0455 (EVAP large leak detected) may be set in the ECM.
   ↓→

2. 2Finding the cause

   Possible causes

   • P0455 sets because of a large leak or a purge blockage: an unseated tube connection, a damaged tube, a canister vent valve stuck open, or a purge valve stuck closed.
   • P0442 sets because of a small leak, which can come from a purge valve stuck open or a canister vent valve stuck open.

   Steps to confirm (in the document’s order)

   1. Inspect every purge connection for proper installation, and look along the lines for damage or wear; if damage is seen, confirm it with the smoke test.
   2. Some leaks show only under pressure and some only under vacuum, so check both ways; cycling the purge and vent solenoids with GDS2 while inspecting may show a sticking valve.
   3. Critical connections to check include: purge tube to purge valve (at the intake manifold), purge tube to chassis EVAP line (rear of the engine, near the transmission), chassis EVAP line to canister, and fuel tank load line to canister.
   4. Also check the vent valve line at the vent valve, the fuel tank load line jumper connection near the fuel tank, and that the fuel tank cap is closed properly.
   5. If all connections are good, check the vent valve for a stuck-open position; if the vent valve works correctly, go on to the purge valve.

   1 more points
   ↓→

3. 3Correction

   Parts

   • No parts are required for this repair.

   Caution

   • For diagnostic instructions, DTC information and required tools, always follow the service information document for the vehicle and DTC being worked on.

Manufacturer communication2000–2006 GMC YUKON DENALI ・ 2022-09-07

MIL Illuminated with Fuel Trim and Oxygen Sensor Codes

1. 1Fault

   • Leak
   • Warning light
   • P0101
   • P0137
   • P0138
   • P0140
   • P0141
   • P0157
   • Customers may comment that the MIL is illuminated.
   • Initial diagnosis may show fuel trim and O2 sensor related codes including P0101, P0137, P0138, P0140, P0141, P0157, P0158, P0160 and P0161.
   • The listed codes also include P0171, P0174, P0420, P0430, P1174 and P1175.
   ↓→

2. 2Finding the cause

   Possible causes

   • These methods find small leaks around the O2 sensor embossments and slight cracks in an intake plenum or gasket.

   Steps to confirm (in the document’s order)

   1. If normal SI diagnostics do not lead to a resolution and an intake vacuum leak or exhaust leak is suspected, use the GE-52250 Variable Pressure Leak Detector (preferred), the J-41416 ultrasonic leak tester, or possibly soapy water with low pressure air into the tailpipe to find the leak.
   2. For an intake leak, introduce the smoke into the brake booster hose or the oil dipstick tube; soapy water can be sprayed near the gasket, seams and all vacuum nipples.
   3. For an exhaust leak, put the hose with smoke or air into the tailpipe sealed with shop towels, then spray soapy water around seals, seams and bosses.
   ↓→

3. 3Correction

   Parts

   • No parts are required for this repair.

   Caution

   • All of these tests are much more effective if the throttle body is covered or sealed.

Manufacturer communication2000–2006 GMC YUKON DENALI ・ 2021-04-19(3 earlier editions of this document folded here)

Induction System Icing Inspection in Cold Ambient Temperatures

1. 1Fault

   • Warning light
   • The check engine light comes on and engine performance is poor in very cold ambient temperatures.
   ↓→

2. 2Finding the cause

   Not stated

   ↓→

3. 3Correction

   This Preliminary information communicates to the technician the need to inspect the induction system for potential icing issues in very cold ambient temperatures. To allow the ice to melt so that it can be drained from the related components. That any of the listed DTC's may set with or without poor engine performance. Â

Manufacturer communication2000–2006 GMC YUKON DENALI ・ 2024-07-16(2 earlier editions of this document folded here)

Fuel Injection Cleaner Kit Service Bulletin

1. 1Fault

   • Hard start or long crank
   • Misfire or rough idle
   • Does not start
   • Warning light
   • Check engine / Service Engine Soon
   • P0300
   • P0301
   • P0302
   • P0303
   • P0304
   • P0305
   • Rough idle, crank no start, extended crank or misfire, with the engine warning lamp on and DTC P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307 or P0308 set.
   • When the engine is cold, compression on multiple cylinders may be zero.
   • The engine may pop through the intake or exhaust while cranking, and the spark plugs may be fuel fouled.
   ↓→

2. 2Finding the cause

   Possible causes

   • Major carbon build-up on the intake and/or exhaust valves from fuel contamination or incomplete burning of the fuel; misfires should not appear before at least 8,000 km (5,000 mi).
   ↓→

3. 3Correction

   • Intake Valve: cleaned

   Repair

   1. If there is no valve damage and no cam follower out of place, perform the cleaning procedure to free sticking valves and remove carbon from the valves and pistons.
   2. If valves are damaged or cam followers are out of place, make the engine mechanical repairs first and then perform the cleaning procedure to prevent a return.
   3. Fill Cleaner Kit J-35800-A with about 650 ml (22 oz, 2 cans) of Air Intake, Combustion Chamber Cleaner and set the air pressure at the tool to 260 kPa (40 psi).
   4. With GDS 2 or a scan tool, command engine idle to 2000 rpm so the engine does not stall.
   5. With the engine at operating temperature in a well-ventilated area, slowly and carefully induce the cleaner into the engine, taking about 3 minutes.

   Parts

   • The Top Engine Cleaning Kit (ACDelco Air Intake, Valve and Combustion Chamber Cleaner and ACDelco Fuel System Cleaner 44K) is 19435372 for the U.S. and Canada.

   Part numbers printed in the document

   • 19435372MAINTENANCE KIT,FUEL SYSTEM ACDELCO 3-11OZLook up at RockAuto (aftermarket candidates) ↗Search the web ↗

     No successor statedas stated by GMPartsGiant (checked 2026-10-06) ↗

   The numbers are as the document prints them. The name and the replacing number are what the pages of GMPartsGiant, a reseller of genuine parts and not GM, state. Aftermarket equivalents are not checked here (the links only search by number). Confirm the fit for the vehicle (VIN) before ordering.

   Caution

   • Inducing too much cleaner at too low an RPM, or stalling the engine with too much cleaner at once, may hydro-lock the engine and bend a connecting rod.

Manufacturer communication2000–2006 GMC YUKON ・ 2023-09-18(4 earlier editions of this document folded here)

Misfire and DTC Codes Diagnostic Information

1. 1Fault

   • Misfire or rough idle
   • Warning light
   • P0300
   • P0308
   • P050D
   • With DTC P0300 - P0308 and/or P050D, use GDS and save the freeze frame records.
   ↓→

2. 2Finding the cause

   Steps to confirm (in the document’s order)

   1. Perform the relative compression test in the PICO NVH or Oscilloscope software; SI Document number 5518386 covers the procedure.
   2. If it passes the relative compression test, the concern is an ignition or fuel delivery issue.
   3. Check the ignition supply voltage to the ignition module/coil assemblies and also to the fuel injectors.
   4. Inspect the spark plugs for anything abnormal.
   5. Note the fuel trim values and on which bank, and compare actual MAF with calculated air flow.

   2 more points
   ↓→

3. 3Correction

   Caution

   • The injector balance procedure in GDS is only a preliminary test and its results should not decide injector replacement, especially with a low or no flow injector.

Manufacturer communication2000–2006 GMC YUKON DENALI ・ 2020-08-10(1 earlier editions of this document folded here)

Needle Bearings in Roller Rockers During Oil Change

1. 1Fault

   • Needle bearings may be found in the oil pan during an oil change.
   ↓→

2. 2Finding the cause

   • Roller Rocker: failed

   Steps to confirm (in the document’s order)

   1. If roller rocker arm needle bearings are found during an oil change, inspect all the roller rocker arms.
   2. There should be 66 bearings, 33 a side.
   ↓→

3. 3Correction

   • Oil Drain: cleaned
   • Roller Rocker: replaced

   Repair

   1. Replace only the broken roller rocker arm; the remaining roller rocker arms need not be replaced.
   2. Needle bearings may also be in the cylinder head oil drains; clean the oil drains to retrieve them.

   Caution

   • The oil pan does not need to be removed: the needle bearing is larger than the oil pump pickup screen mesh and cannot be pulled into the oil pump.

Manufacturer communication2000–2006 GMC YUKON DENALI ・ 2019-06-10

Torque Converter Bolt Removal Warning

1. 1Fault

   • Noise
   • Customers may comment on noise coming from underneath a vehicle equipped with an automatic transmission.
   • Technicians may find that the noise is coming from the bell housing area.
   ↓→

2. 2Finding the cause

   Possible causes

   • Running the engine with those bolts removed may damage the pilot on the front of the torque converter, the pilot hole in the end of the crankshaft, or both.

   Steps to confirm (in the document’s order)

   • Use chassis ears to isolate the component or assembly that is the loudest source of the noise.
   ↓→

3. 3Correction

   Caution

   • Do not remove the flex plate to torque converter bolts, push the converter back toward the transmission and start the engine to decide whether the noise comes from the engine or the transmission.