P2D23

Code

Generic P — Powertrain

Turbocharger Interstage Pressure Sensor A Circuit Low

Brand: Generic

Type: P — Powertrain

Views: UK: 30 EN: 44 RU: 30

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Page language: EN

Causes

Short to ground on the sensor signal circuit
Open or high-resistance connection in signal, reference, or ground wires
Failed or out-of-spec interstage pressure sensor (A)
Low or missing sensor reference voltage from ECM (5V or 3.3V depending on vehicle)
Poor connector pin contact, corrosion, or water ingress
ECM input circuit fault

Symptoms

Reduced engine power or limp mode under boost conditions
Illuminated malfunction indicator lamp (MIL / check engine light)
Incorrect boost control behavior or turbo surge
Stored related boost/pressure fault codes
Possible hard starting or rough idle if ECM uses sensor for fueling

What to check

Read freeze frame and live data for interstage pressure sensor A signal and compare to expected values
Visually inspect sensor, connector, and harness for damage, oil contamination, or corrosion
Check for related codes (other pressure/boost sensor faults) and ECM data
Backprobe sensor connector to measure signal, reference voltage, and ground with key ON and engine running (if safe)
Perform wiring continuity and resistance checks from sensor pins to ECM pins with harness disconnected
Check for short to ground or short to voltage on the signal wire

Signal parameters

Expected sensor reference voltage: typically 5.0 V (some systems 3.3 V) with key ON
Expected sensor signal idle/atmosphere: ~0.5 V to 1.5 V (varies by sensor); should rise with boost toward reference voltage (often up to ~4.5 V)
A true 'circuit low' will show signal near 0.0–0.2 V or fixed very low regardless of boost
Sensor ground should be close to 0.0 V (low milliohms to vehicle ground)
Typical sensor output impedance: low; open-circuit reads very high resistance or infinite

Diagnostic algorithm

Retrieve codes and freeze frame; note engine conditions when code set (RPM, load, boost).
Visually inspect sensor, vacuum/pressure lines (if present), connector and wiring for damage, oil intrusion, or corrosion. Repair visible damage.
With connector connected, backprobe: measure reference voltage at sensor pin with key ON. If missing or out of spec, trace power/reference feed (fuse, relay, ECM pin).
Measure sensor signal voltage with engine off and during a controlled rev or boost event (use safe test conditions). If signal remains very low (~0 V), suspect short to ground or sensor fault.
Disconnect sensor and measure resistance between signal wire and ground to check for short to ground. Check continuity between sensor signal pin and ECM input pin; check continuity and for high resistance.
If wiring appears good, bench-test or replace sensor with known-good unit and re-check signal behavior.
If new sensor still reads low, check ECM connector pins for damage, and verify ECM grounds and power rails. Consider ECM input circuit testing or module replacement only after wiring and sensor confirmed good.
Clear codes and perform a road test to confirm repair. Monitor live data for consistent, plausible interstage pressure readings across operating range.

Likely causes

Damaged or chafed harness where it routes near turbocharger or hot components
Corroded or pushed-out terminal at sensor connector
Sensor contaminated with oil/soot or mechanically blocked
Sensor internal failure (shorted output or internal ground)
Blown fuse or failed voltage regulator feeding sensor reference

Fault status

⚠️ Status

P2D23 - Turbocharger Interstage Pressure Sensor A Circuit Low: sensor signal lower than expected (possible short to ground, bad sensor, wiring, or reference/ground fault).

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours