The 2004 XG350 was Hyundai's first serious attempt at a luxury sedan, sharing its 3.5L V6 (Sigma engine) with the Santa Fe. While comfortable and well-equipped, this platform suffers from catastrophic engine failure issues and transmission cooling problems that can total the car if ignored.
Symptoms: Excessive oil consumption (1+ quart per 1,000 miles), Rod knock or deep knocking from bottom end at startup, Metal shavings in oil or oil filter, Low oil pressure warning with adequate oil level, White or blue smoke from exhaust under load
Fix: The Sigma V6 is notorious for piston ring land failure and bearing wear, often requiring complete engine rebuild or replacement. Ring job alone is 18-22 hours, but most need short block or full longblock replacement at 25-30 hours labor due to cylinder scoring. Used engines are scarce and risky.
Symptoms: Milky or strawberry-colored transmission fluid (coolant mixing), Transmission slipping or delayed engagement after engine reaches temp, Coolant level drops without external leaks, Transmission overheating warnings, Engine overheating in some cases
Fix: Internal transmission cooler in radiator corrodes and allows coolant/ATF mixing, destroying the transmission. Requires radiator replacement, complete transmission fluid system flush (sometimes external cooler install), and often transmission rebuild if contamination went unnoticed. Preventive external cooler is 2-3 hours, full damage repair is 12-18 hours.
Estimated cost: $800-4,200
Transmission Mounts Collapsing
Common · medium severity
Typical onset: 60,000-100,000 mi
Symptoms: Harsh clunk when shifting from Park to Drive or Reverse, Excessive engine movement visible from engine bay during throttle blips, Vibration through chassis at idle in Drive, Transmission tunnel heat or rattling noises
Fix: The front and rear transmission mounts wear rapidly on this transverse V6/transaxle setup. Front mount replacement is 2-3 hours, rear is 1.5-2 hours. Replace both simultaneously as labor overlaps. OEM rubber quality was poor.
Estimated cost: $350-650
Head Gasket Failure (Both Banks)
Occasional · high severity
Typical onset: 90,000-150,000 mi
Symptoms: External coolant weeping from cylinder head mating surface, White exhaust smoke with sweet smell, Overheating with no obvious coolant leaks, Combustion gases in cooling system (bubbling in overflow tank), Rough idle or misfire after engine sits overnight
Fix: Gasket failure often coincides with or follows from overheating due to cooler failure. Both heads should be done simultaneously (14-18 hours labor), and heads must be checked for warpage. Often discovers additional piston/ring damage requiring full teardown.
Estimated cost: $2,200-3,800
Fuel Filter Clogging / Fuel Delivery Issues
Occasional · medium severity
Typical onset: 80,000-120,000 mi
Symptoms: Hesitation or stumbling under acceleration, Hard starting after sitting, especially when hot, Loss of power at highway speeds, Check engine light with lean codes (P0171/P0174)
Fix: In-tank fuel filter is not regularly serviced and clogs over time, especially with ethanol fuel. Requires fuel pump module removal (3-4 hours). While in there, inspect pump itself as failures are common after 100k. Preventive replacement every 60k would avoid this.
Estimated cost: $400-700
Lower Control Arm Bushings and Ball Joints
Common · medium severity
Typical onset: 70,000-110,000 mi
Symptoms: Clunking over bumps from front suspension, Steering wander or loose feel on highway, Uneven tire wear on inside edges, Steering wheel off-center after hitting potholes
Fix: Front lower control arms use pressed-in bushings and integrated ball joints that wear prematurely. Replace entire control arms (2-3 hours per side) rather than attempting bushing replacement. Alignment mandatory afterward. Related to NHTSA suspension recall—verify recall completion.
Estimated cost: $500-900
Owner tips
Check oil level every fillup—consumption is early warning of engine death. Budget $200/month for oil top-offs if buying high-mileage.
Inspect transmission fluid color monthly; any pink tint means immediate radiator replacement before transmission dies.
Install external transmission cooler preemptively ($250-400)—cheap insurance against the $4k transmission replacement.
Verify NHTSA suspension recall (front lower control arms) was completed—check VIN at NHTSA.gov.
Avoid any XG350 with unknown service history or signs of overheating—engine damage is likely already done.
Only buy with complete records proving transmission cooler was upgraded and engine has never overheated; otherwise, budget $5k-8k for inevitable catastrophic repairs within 20,000 miles.
AI-assisted summary drawn from NHTSA recall data, our labor-times database, and platform knowledge. Not a substitute for a pre-purchase inspection on a specific vehicle.
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Every control module on the 2002-2005 Hyundai XG350 — where it lives, replacement time, and what it takes to program a replacement. Modules marked dealer / factory tool won't work after a part swap alone — budget for programming.
Electronic Power Steering Module (MDPS)2.5 hr R&Rrelearn only +0.3 hr▸ programming details
📍 Steering column, integrated with steering column assembly or on steering rack
🔧 Hyundai GDS or aftermarket scan tool
⚠️ Steering angle sensor calibration required; available on late 2004-2005 models only
Anti-lock Brake System Module (ABS)2.0 hr R&Rno coding
📍 Engine compartment, driver side near master cylinder, integrated with hydraulic unit
⚠️ Brake bleeding required after replacement; module integrated with hydraulic control unit
Transmission Control Module (TCM)1.5 hr R&Rrelearn only +0.2 hr▸ programming details
📍 Engine compartment, driver side near battery, mounted to inner fender or on transmission bell housing
📍 Dashboard, behind instrument panel bezel, secured with screws
🔧 Hyundai GDS
⚠️ Mileage programming required by dealer; immobilizer synchronization needed
Immobilizer Control Unit (IMU/IMMO)0.8 hr R&Rdealer / factory tool +1.0 hr▸ programming details
📍 Dashboard area, near ignition switch or integrated with BCM
🔧 Hyundai GDS or specialized locksmith tool
⚠️ All keys must be reprogrammed after replacement; may be integrated with BCM on some builds
Audio Head Unit (AVN)0.6 hr R&Rrelearn only +0.2 hr▸ programming details
📍 Center dashboard, in radio slot above climate controls
🔧 Enter radio code from owner's manual or dealer
⚠️ Anti-theft radio code required after battery disconnect or replacement
Aftermarket tool coverage varies by software version and vehicle build — treat "aftermarket tool" rows as "usually possible" and verify against your tool maker's coverage list before promising a customer. Spot a wrong location or hour? Tell us — corrections ship fast here.
HYUNDAI IS RECALLING 188,282 MY 2001-2004 SONATA AND MY 2001-2004 XG300 AND XG350 VEHICLES ORIGINALLY SOLD IN OR CURRENTLY REGISTERED IN THE STATES OF CONNECTICUT, DELAWARE, ILLINOIS, INDIANA, IOWA, MAINE, MARYLAND, MASSACHUSETTS, MICHIGAN, MINNESOTA, MISSOURI, NEW HAMPSHIRE, NEW JERSEY, NEW YORK, OHIO, PENNSYLVANIA, RHODE ISLAND, VERMONT, WEST VIRGINIA, WISCONSIN, AND THE DISTRICT OF COLUMBIA. ROAD SALT APPLIED IN THESE JURISDICTIONS DURING THE WINTER MONTHS MAY RESULT IN PROGRESSIVE, INTERNAL CORROSION OF THE FRONT SUB-FRAME ON THE VEHICLES, AND MAY RESULT IN THINNING OR PERFORATION OF THE SUB-FRAME STEEL. THE CORROSION IS FREQUENTLY VISIBLE AND OFTEN DISCOVERED DURING INSPECTION OR ROUTINE MAINTENANCE, AND OWNERS MAY ALSO HEAR NOISES OR NOTICE TIRE MISALIGNMENT AND STEERING PULL. IF THESE SIGNALS ARE UNDETECTED OR UNHEEDED, THE CORROSION MAY PROGRESS AND THE FORWARD MOUNTING OF THE LOWER CONTROL ARM MAY DETACH FROM THE SUB-FRAME.
Consequence: IF THAT HAPPENS, THE VEHICLE MAY LOSE DRIVE POWER TO THE WHEELS, AND THE FRONT WHEEL MAY MAKE CONTACT WITH THE FENDER OR WHEEL WELL, THEREBY INCREASING THE RISK OF A CRASH.
Remedy: DEALERS WILL MEASURE THE THICKNESS OF THE FRONT SUB-FRAME AND INSPECT THE FRONT SUB-FRAME FOR CORROSION DAMAGE AND, IF NECESSARY, THE FRONT SUB-FRAME WILL BE REPLACED WITH A NEW SUB-FRAME THAT INCORPORATES ADDITIONAL HOLES IN THE UPPER AND LOWER PANELS. IF THE FRONT SUB-FRAME DOES NOT REQUIRE REPLACEMENT, THE DEALER WILL ADD DRAINAGE HOLES TO THE SUB-FRAME AND WILL TREAT THE SUB-FRAME WITH RUST-PROOFING MATERIAL TO STOP THE CORROSION PROCESS. THIS PROCEDURE WILL BE PERFORMED FREE OF CHARGE. THE RECALL IS EXPECTED TO BEGIN DURING APRIL 2009. OWNERS MAY CONTACT THE HYUNDAI CUSTOMER ASSISTANCE CENTER AT 1-800-633-5151.
Size-standard part numbers — verify your connector type before buying. Rear blades are model-specific; check the package's vehicle list.
Fuel economy figures are EPA data via fueleconomy.gov (median across matching trims). Performance figures are compiled estimates for the 2004 Hyundai XG350 3.5L V6 and can vary by trim.
🔧 Database maintained under the daily editorial review of Chris Hackleman · Master Technician · 20+ years and Jeff Moore · Master Mechanic · 20+ years.