MAF Circuit Range/Performance
The PACCAR-P0101 (PACCAR MX) diesel fault code means: MAF Circuit Range/Performance. This is a moderate severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- intermediate
- Estimated cost
- $300-$3,500
Down with a PACCAR fault on the road?
Get connected with a verified mobile diesel mechanic near you. Verified diesel & reefer techs, launching on the freight corridor.
Find a mobile mechanic →A $30 car code reader can't do diesel. The HD7000 reads full-system codes and does parked DPF regen, idle/speed-limit, and service resets from the cab — on everything from a 6.7 Cummins/Power Stroke/Duramax pickup to Class-8 trucks (Detroit, Paccar, CAT, Volvo, Mack, International).
Check Price on AmazonAffiliate link -- we earn a commission at no extra cost to you.
Full-system 6/9/16-pin diesel scan tool for Cummins, Paccar, CAT, Detroit and more — plug-and-play, no subscription. A cheaper way to read heavy-duty codes a basic OBD2 scanner skips entirely.
Check Price on AmazonAffiliate link -- we earn a commission at no extra cost to you.
Common Symptoms
- Check Engine Light illuminated
- Performance loss or engine derate
- Rough idle, hard starting, or stalling
- Scan tool communication issues (U-codes)
- Possible smoke or unusual noise
Probable Causes (Ranked by Likelihood)
- Sensor or actuator failure in the affected circuit Likely
- Wiring harness damage, chafing, or corrosion Likely
- Contaminated fuel / DEF / coolant Possible
- ECM or CEM needs reflash for known calibration issue Possible
- Mechanical wear (high-mileage truck) Possible
Step-by-Step Diagnostic Procedure
Pull all active and inactive codes from ECM, CEM, ABS, and TCM with DAVIE4 — root cause often sets multiple codes.
Capture freeze frame data and compare values to known good operating ranges.
Back-probe the affected sensor / actuator circuit with a DMM key-on engine-off and running.
Inspect wiring harness at valve cover, turbo, and frame crossover points for chafing / rub-through.
After repair, clear codes and perform a road-test drive cycle to verify fault does not return.
Common Fixes by Vehicle
What techs usually find when diagnosing PACCAR-P0101 on specific platforms — tap a platform for the fix and the exact part:
2013-2019 Kenworth/Peterbilt PACCAR MX-13 Easy DIY
P0101 (mass airflow sensor) on the MX-13 is often a contaminated MAF sensor or a cracked intake pipe between the air filter and turbo. Inspect the intake system for soot accumulation or cracks. Clean the MAF with electronics cleaner (not carb cleaner). If the code persists, replace the MAF -- OEM PACCAR MAF is $200-$400. Check the air filter restriction indicator while you're at it.
Labor: 30-60 minFrequently Asked Questions
What does PACCAR MX code P0101 mean?
PACCAR MX code P0101 (MAF Circuit Range/Performance) is a moderate-severity diagnostic trouble code set by the engine or aftertreatment control module on MX-11 and MX-13 engines in Kenworth and Peterbilt trucks. It indicates a fault in the air system that should be diagnosed with DAVIE4 or PACCAR ESA.
Can I drive a Kenworth or Peterbilt with PACCAR P0101?
Possibly — short distances may be OK, but ignoring the fault risks progressive damage, regen failure, or derate. Address promptly.
How much does it cost to fix PACCAR MX P0101?
Typical repair runs $300-$3,500. Sensor or wiring repairs are at the low end; injector, DEF pump, DPF, or EGR cooler jobs are at the high end. Dealer-level DAVIE4 software is often required for programming or calibration after parts replacement.
Sources
This page is built from documented references. Verify against your own service info before repair work.
P0101 on Other Platforms
The same code ID appears across other engines, vehicles, and equipment. Diagnostic flow varies by platform — see the matching breakdown: