Valve Lash Adjustment Interval Due (Volvo/Mack Preventive Service)
The VOLVO-MACK-VALVE-LASH-INTERVAL (Volvo/Mack D/MP Series) diesel fault code means: Valve Lash Adjustment Interval Due (Volvo/Mack Preventive Service). This is a minor severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- intermediate
- Estimated cost
- $600-$1,200
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Common Symptoms
- No active fault code — this is a preventive service indicator only
- Valve tick increasing at idle
- Slight loss of top-end power
- Slightly increased fuel burn
- Elevated EGT under load
Probable Causes (Ranked by Likelihood)
- Valve lash drift is normal wear; Volvo spec: adjust at 250K miles initially, then every 500K miles (verify current service bulletin for the engine year) Very Likely
- Valve recession into head from high mileage Likely
- Rocker arm wear at adjusting screw contact Possible
- Hardened valve seat wear (EGR service contributes) Possible
- Camshaft lobe wear (rare) Less Likely
Step-by-Step Diagnostic Procedure
Pull service records and confirm mileage interval against current Volvo/Mack bulletin.
Warm engine to operating temperature, then shut down; bring the engine to TDC compression for the cylinder being adjusted.
Check lash with a feeler gauge per the current spec sheet (intake and exhaust values differ and change by engine family).
Adjust using Volvo/Mack special tool; torque locking nut to spec.
Reset the valve-lash service interval counter via Volvo PTT or Mack Guided Diagnostics.
Document adjustment in maintenance records for warranty and fleet tracking.
Frequently Asked Questions
What does Volvo/Mack code VALVE-LASH-INTERVAL mean?
Volvo/Mack code VALVE-LASH-INTERVAL (Valve Lash Adjustment Interval Due (Volvo/Mack Preventive Service)) is a minor-severity diagnostic trouble code set on D11/MP7, D13/MP8, and D16/MP10 diesel engines in Volvo VNL/VNR and Mack Anthem/Pinnacle/Granite/Titan trucks. It indicates a fault in the valvetrain system and should be read with Volvo Premium Tech Tool (PTT) or Mack Guided Diagnostics.
Can I drive a Volvo or Mack truck with code VALVE-LASH-INTERVAL?
Limited short-term operation is usually possible, but the fault will illuminate the Check Engine Light and should be diagnosed promptly to avoid cascading aftertreatment or fueling faults.
How much does it cost to fix Volvo/Mack code VALVE-LASH-INTERVAL?
Typical repair falls in the range $600-$1,200. Sensor/wiring repairs are at the low end; EGR cooler, NOx sensor set, DEF pump, injector, or head work runs at the high end. Volvo PTT or Mack Guided Diagnostics is normally required for calibration and parameter programming.