P0894 on GMC: How to Diagnose & Fix
Transmission Component Slipping
1 GMC model · 2 documented issues · 1 critical · $150-$3,000 repair
P0894 on GMC by model: symptoms, diagnosis and fix
GMT900 and early K2XX Yukon XL models with 6L80/6L90 transmissions commonly develop leaks at the transmission cooler line crimps or quick-connect fittings. Owners report red fluid spots, low transmission fluid, and in severe cases slipping or overheating if fluid loss is significant. This issue is widely documented in owner reports and GM service bulletins addressing cooler line seepage/connection concerns on full-size trucks/SUVs using these transmissions.
Common Symptoms
- Red transmission fluid spots under front of vehicle
- Burnt ATF smell after driving
- Transmission slipping or delayed engagement
- Transmission over-temp message (if severe)
How to Fix
Replace the leaking transmission cooler line(s) or fitting seals; many repairs involve replacing the entire line assembly rather than re-crimping. After repair, verify fluid level with the correct ATF (Dexron VI for 6L80/6L90) and check for overheating-related damage.
Sources for this issue (1)
The 8-speed (8L90) and 10-speed (10L80) automatic transmissions in the Yukon XL develop a torque converter clutch (TCC) shudder felt as a vibration or shake at light throttle between 25-50 mph. The shudder mimics driving over rumble strips. GM issued multiple TSBs (18-NA-355, 19-NA-193) and eventually reformulated the transmission fluid specification. The root cause is the TCC friction material interaction with the original Dexron HP fluid formulation.
Common Symptoms
- Vibration or shudder at 25-50 mph under light throttle
- Feels like driving over rumble strips
- Shudder disappears under heavy acceleration
- Vibration most noticeable in overdrive gears
- Intermittent — may come and go
How to Fix
First-line fix: complete transmission fluid flush and fill with GM-approved Mobil 1 Synthetic LV ATF HP (Blue Label) — NOT the original red-label Dexron HP. This updated fluid resolves the shudder in approximately 80% of cases. If shudder returns within 30,000 miles of the fluid change, the torque converter requires replacement. Do NOT use aftermarket friction modifiers or additives — they void the GM powertrain warranty and can damage the transmission.
Sources for this issue (1)
P0894 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0894 mean on a GMC?
P0894 stands for "Transmission Component Slipping." This generic transmission code means the PCM/TCM detected that a rotating component inside the transmission is slipping, by comparing input and output speeds and finding more difference than there should be for the commanded gear. Slippage indicates clutches or bands are not holding properly, which can quickly worsen and damage the transmission through overheating and accelerated wear. It often comes with rough or flaring shifts, reduced power, and overheating, and should be addressed promptly. On GMC it is documented across 1 model: Yukon XL.
What are the most common causes of P0894?
The most common causes of P0894 are: Low, dirty, or burnt transmission fluid, Worn clutch packs or bands, Faulty shift or pressure control solenoid, Internal hydraulic/valve body problems, Worn torque converter, Faulty speed sensors giving false slip readings, General internal transmission wear. The specific cause varies by vehicle.
How much does it cost to fix P0894 on a GMC?
Published repair estimates on GMC range from $150 to $3,000 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P0894 on a different make?
View P0894 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.