Do I need a 2-bar or 3-bar MAP sensor operating system for a boosted LS?
Match the sensor and operating system to your boost: a 2-bar MAP (GM 16040609) with a 2-bar OS covers up to about 14 psi; a 3-bar MAP (GM 12223861) with a 3-bar OS covers up to about 29 psi at sea level. On P01/P59 you apply HP Tuners' custom 2/3-bar speed-density OS, which costs extra credits; on E38/E67 most calibrations need no OS change — you enter the sensor's linear/offset values and set the VVE MAP range to 10-210 or 10-315 kPa.
Last updated
Who this applies to
- Computers: P01, P59, E38, E67
- Engines: LS1, LS2, LS3, LS6, LS7, LM7, LQ4, LQ9, LY6, L96, L92
- Transmissions: 4L60E, 4L80E, 6L80E, T56
- Not for: E92 Gen V; any 1-bar MAP sensor under boost (reads no boost at all)
P01/P59 boosted
- Apply the matching custom OS: OS tab → 2-bar or 3-bar speed-density OS (with real-time tuning if wanted). up to 5 extra credits
- Install the matching MAP sensor: 2-bar GM 16040609 (linear 207.66 / offset 9.00 kPa) or 3-bar GM 12223861 (linear 329.41 / offset -6.35 kPa). 207.66/9.00 (2-bar); 329.41/-6.35 (3-bar)
- Copy the NA VE values up to 105 kPa into the new OS table, then extend and tune the boost columns; set up boost enrichment so PE isn't the only fuel adder. seed to 105 kPa, then extend
- Fail the MAF (0 Hz) if running MAF-less; pull timing in boost areas until dyno-tuned. 0 Hz; pull timing in boost
E38/E67 boosted
- Install the 2-bar or 3-bar MAP sensor and enter its linear/offset in the MAP sensor calibration. 207.66/9.00 (2-bar); 329.41/-6.35 (3-bar)
- Edit > Virtual VE: set the MAP axis range to 10-210 kPa (2-bar) or 10-315 kPa (3-bar); keep manifold-open and manifold-closed tables identical. 10-210 / 10-315 kPa
- Tune the VVE with a wideband; recalculate coefficients after each correction pass.
Careful
- The sensor and the OS must match — a 3-bar sensor on a 2-bar calibration wrecks global fueling.
- Enter the linear/offset for your sensor; don't copy someone else's 3-bar numbers.
More in fuel, E85 & boost, or build a checklist for your swap with the tune checklist tool.
Go deeper
Check this first
- Log MAP kPa in boost: if it flatlines around 105 kPa while boost rises, the 1-bar sensor/OS is maxed and blind up top.
- Check that the VE/VVE table's MAP axis extends past 105 kPa — if it stops there, the boost OS or VVE range was never set up.
Try this, then this
- Pick 2-bar for up to ~14 psi, 3-bar for more (3-bar reads ~29 psi at sea level). — The sensor must see the whole boost range or fueling goes blind up top. Worked if: Logged MAP reaches target boost.
- P01/P59: apply the matching custom OS before installing the sensor. — The custom OS carries the expanded VE table; the stock OS stops at ~105 kPa. Worked if: The VE axis extends past 105 kPa.
- E38/E67: enter the sensor's linear/offset and set the VVE MAP range. — No custom OS is needed — the ECM just needs the sensor curve and the axis. Worked if: KOEO reads baro and the VVE spans the range.
- Seed the boost VE cells from the NA table up to 105 kPa, then tune with a wideband; keep timing conservative until the dyno. — A fresh boost table at max values won't start the engine; a copied-and-extended table will. Worked if: Wideband matches commanded under boost.
How you know it's fixed
- MAP tracks smoothly from vacuum past 105 kPa up to target boost, and fueling follows the VE/VVE table with no PE-only fudge.
- Key-on/engine-off reads barometric pressure correctly, confirming the linear/offset matches the sensor.
Key numbers
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| What | Value |
|---|---|
| Custom OS boost ceiling (3-bar) | up to 30 psi |
| Custom OS cost (P01/P59) | up to 5 extra credits |
| Sensor must match the OS | matching sensor required |
| 2-bar MAP scaling | GM 16040609, linear 207.66, offset 9.00 kPa |
| 3-bar MAP scaling | GM 12223861, linear 329.41, offset -6.35 kPa |
| 3-bar boost reading at sea level | about 29 psi of boost |
| E38 VVE MAP ranges | 10-210 kPa (2-bar), 10-315 kPa (3-bar) |
| Use your sensor's values, not a copy | enter per-sensor values |
Every option we know of
| Maker / product | Part # | Fits | Price | Where | Status / notes |
|---|---|---|---|---|---|
| GM 2-bar MAP sensor | 16040609 | GM 3-pin MAP connector (pin 1 = 5V, pin 2 = signal, pin 3 = ground) | Buy used/NOS market | Discontinued / used only discontinued; verify linear/offset per sensor | |
| GM 3-bar MAP sensor | 12223861 | GM 3-pin MAP connector | Buy used/NOS market | Discontinued / used only discontinued; verify linear/offset per sensor | |
| GM 3-bar MAP sensor (LSA/LS9 style) | 12592525 | LS3-style bolt-hole manifolds (per existing page) | Buy | verify scaling against the sensor datasheet | |
| Holley MAP adapter harness | 558-416 | Terminator X boosted installs (per existing page) | Buy |
Prices are approximate as of September 2026. We list every option we know of, including small shops and used parts we can't link to. Confirm fitment with the seller.
Time and cost: Sensor cost plus, on P01/P59, up to 5 extra HP Tuners credits; the real cost is the boost tuning time.
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