What does it mean?
Forced induction engines carry a pressure sensor ahead of the bank 2 compressor so the module knows what pressure the charger is drawing from, and it compares that figure with barometric pressure. With the engine off, or idling with no boost demand, the two values should be almost identical because the compressor inlet simply sees atmosphere through the filter and ducting. This code is stored when the difference between them exceeds the calibrated tolerance under those conditions. That means either one of the two sensors is reporting incorrectly, or the inlet path really is restricted enough to pull the pressure down before the compressor. On a mechanically sound engine a clogged filter or a collapsed duct is one of the first things this test catches.
Symptoms
- MIL on with reduced boost and noticeably weaker acceleration
- Turbocharger noise rising to a whistle or a moan under load
- Black smoke or a rich running condition on diesels as real airflow drops
- limp mode on some vehicles when the boost error stays large
- Poor fuel economy and slow throttle response
- A visible gap between barometric and inlet pressure on a scan tool with the key on and engine off
Likely causes
- Air filter clogged, or an intake duct crushed, collapsed or obstructed ahead of the bank 2 compressor
- Turbocharger inlet pressure sensor drifted, fouled with oil or physically damaged
- Barometric pressure source reading incorrectly, whether a separate sensor or the barometric function inside the manifold pressure sensor
- Loose or split inlet ducting between the filter and the compressor
- Wiring or connector resistance on the inlet pressure sensor producing a small offset instead of a full circuit failure
- Debris, ice or a displaced inlet screen partly blocking the air path
- Calibration mismatch after module replacement, or an aftermarket intake that changes inlet restriction
How to fix it
- Compare barometric pressure and turbocharger inlet pressure with the key on and the engine off; both should be close to each other and to actual local atmospheric pressure
- Inspect the complete bank 2 inlet path, including the filter, box seal, snorkel and any resonator, and remove restrictions
- Run the engine and look for ducting that softens or collapses under suction
- Check the inlet pressure sensor port and element for oil, soot, water or ice and clean or renew a fouled sensor
- Test the sensor circuits for reference voltage, ground quality and signal integrity, repairing any high resistance found
- Confirm the barometric value is credible against known local pressure before condemning the inlet sensor
- Recheck the correlation after repair with a road test that reaches full boost