LZ0 3.0 Duramax Crankshaft End Play – GM Issues Bulletin 25-NA-307
What’s the Problem
General Motors has issued Service Bulletin 25-NA-307 addressing a new concern in vehicles equipped with the LZ0 3.0L Duramax inline-six diesel engine. Owners have reported mechanical noise from the bellhousing area, accompanied by a Check Engine Light and DTC P06DD (“Engine Oil Pressure Control Valve Performance”).
According to GM, the issue may stem from crankshaft end play—axial movement of the crankshaft beyond the specified tolerance—caused by thrust bearing wear or internal clearance defects. When out of spec, the condition can lead to erratic oil-pressure control, internal engine damage, and recurring MIL illumination.
This affects 2025–2026 model year Chevrolet Silverado 1500, Suburban, Tahoe, and GMC Sierra 1500, Yukon, and Yukon XL vehicles equipped with the LZ0 Duramax engine.
Allegations
GM’s bulletin confirms that excessive crankshaft end play can cause both mechanical noise and the P06DD fault code. The company instructs technicians to measure the crankshaft’s movement using a dial indicator. Acceptable limits are:
0.084–0.316 mm (0.0033–0.0124 inches)
If movement exceeds those limits, the bulletin directs dealers to inspect and repair the thrust bearing and crankshaft assembly.
While this is not classified as a recall, it represents a manufacturer acknowledgment that internal engine movement can trigger oil-pressure faults. For owners who have experienced multiple unsuccessful repairs or recurring noise and codes, this can support a potential lemon law claim.
Recall / TSB
GM TSB 25-NA-307 instructs technicians to:
Remove the torque-converter access cover.
Pry the torque converter forward and backward to load and unload the crankshaft.
Measure total crankshaft end play using a dial indicator.
Compare results to the specified tolerance.
If out of range, inspect and repair the crankshaft thrust surfaces.
If within range, technicians must continue diagnosing the P06DD fault per standard GM procedures (oil control valve, sensor wiring, oil-pressure solenoid, etc.).
Because this is a service bulletin, not a recall, owners will not receive notice. It is only visible to dealerships within GM’s internal service network.
Symptoms
Owners of LZ0 Duramax trucks may notice one or more of the following:
Rattling, tapping, or clunking noise from the bellhousing area
Check Engine Light with code P06DD
Low or fluctuating oil-pressure readings
Vibration near the transmission tunnel
Multiple service visits without a confirmed fix
Noise may vary depending on temperature and load, making it difficult for technicians to reproduce. If you’ve had multiple visits for this issue, ensure your repair order documents the noise, the code, and whether the bulletin procedure was followed.
How to Proceed
Document Issues: Keep detailed records of all repairs, warning lights, and dealership communications. Request that each repair order specifically mention “25-NA-307” and whether crankshaft end play was measured.
Reasonable Number of Repair Attempts: While the law doesn’t state an exact number, generally if the same issue persists after four or more repair attempts, or if your vehicle has been out of service 30 days or more cumulatively, it may qualify as a lemon under California’s Song-Beverly Consumer Warranty Act.
Monitor Symptoms: If you hear continued mechanical noise, oil-pressure warnings, or experience renewed DTC P06DD codes, stop driving and seek immediate inspection.
Talk to a Lemon Law Attorney, like Valero Law: If GM cannot repair your Duramax after repeated visits, you may be entitled to a repurchase, replacement, or cash settlement under California law.
Call Valero Law
If you own a 2025–2026 Chevrolet Silverado, Suburban, Tahoe, GMC Sierra, or Yukon with the LZ0 3.0 Duramax and are experiencing bellhousing noise, low oil pressure, or P06DD codes, you may be protected under the California Lemon Law.
GM’s own bulletin confirms this defect involves internal crankshaft movement—a serious engine concern that can repeat even after repair.
Call Valero Law, APC at (424) 299-4447 or submit a free Lemon Law case evaluation today. All cases are handled on a contingency basis, meaning no cost to you unless we recover.