How do you set up the scanner to tune with a 2-bar or 3-bar MAP sensor on a custom OS?

In VCM Scanner, add the custom 2-bar/3-bar MAP PID that matches your OS. On P01/P59 the PID is tied to the custom OS — search 'bar' in Add Channel, and if it reads 0 kPa, use Repoll for Supported Parameters to refresh the channel list. On E40 and newer, the generic Manifold Absolute Pressure (SAE) PID already reads into boost and there is a built-in Boost parameter. The scanner histograms auto-adjust for the 2-bar/3-bar feature, so VE corrections land on the boost tables correctly.

Last updated October 28, 2026

Who this applies to

• Computers: P01, P59, E40
• Engines: LM7, LQ4, LQ9, LS1, LS2
• Transmissions: all
• Years: 1999-2007
• Not for: E38/E67/E92 (no custom OS needed; scale MAP linear/offset instead)

P01/P59 with 2-bar or 3-bar custom OS, HP Tuners

1. VCM Scanner > Add Channel: search 'bar' and add the 2-bar/3-bar MAP PID matching your OS
2. If the PID reads 0 kPa: VCM Scanner > Repoll for Supported Parameters to refresh the .upf file
3. Tune with the Boost VE histogram from the histogram library — it auto-recognizes the 2/3-bar feature
4. Engine > Airflow > MAP Sensor Linear/Offset: enter your sensor's numbers (GM 2-bar: 200.00/10.34; GM 3-bar: 305.00/10.34) 200.00/10.34 kPa (2-bar); 305.00/10.34 kPa (3-bar)

E40 with 2.5-bar SD OS, HP Tuners

1. Log the generic Manifold Absolute Pressure (SAE) PID — it reads into boost on E40 and up
2. Or use the built-in Boost parameter instead of building a custom one
3. Boost VE spans 105-255 kPa (2.5 bar / 22.5 psi boost) with better than 5 kPa resolution

Careful

• A 2-bar sensor/OS goes blind above ~15 psi boost — anything above is invisible and untunable; size the sensor and OS to your max boost.
• A new MAP range can trip P0106 (MAP performance) — raise the engine-diag P0106 table or disable the code.

More in who tunes it, or build a checklist for your swap with the tune checklist tool.