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Home / DTC / P2438 — AIR System Air Flow/Pressure Sensor Circuit High Bank 2

P2438 — AIR System Air Flow/Pressure Sensor Circuit High Bank 2

Detailed page for trouble code P2438.

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Code

P2438

Generic P — Powertrain

AIR System Air Flow/Pressure Sensor Circuit High Bank 2

Brand: Generic
Type: P — Powertrain
Views: UK: 13 EN: 21 RU: 15
AI status
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Page language: EN

Causes

  • Open or shorted wiring (short to 12V) on the bank 2 air flow/pressure sensor signal circuit
  • Corroded, loose, or damaged connector at the sensor
  • Failed air flow/pressure sensor (internally shorted or damaged)
  • Blown or intermittent sensor power/ground (fuse, ground point, or wiring)
  • Mechanical restriction or over-pressure in the secondary air system affecting the sensor
  • PCM/ECM internal fault (rare)

Symptoms

  • Malfunction Indicator Lamp (MIL) illuminated
  • Possible secondary air injection system fault / reduced emission control (cold-start emissions may increase)
  • Diagnostic trouble codes related to air injection or oxygen sensors may be present
  • Possible rough idle or drivability complaints during cold start (if secondary air injection affected)
  • Possible failed emissions test

What to check

  • Read freeze-frame and stored data with a scan tool; note conditions when the code set (engine temp, RPM, load, ambient temp)
  • Check for other related codes (secondary air, O2 sensors, MAF) that can provide context
  • Visually inspect sensor connector and wiring for corrosion, damage, pin push-out, or moisture
  • Backprobe the sensor connector and check reference voltage, signal voltage, and ground with a multimeter
  • Perform continuity and resistance checks on the signal, power and ground circuits to the PCM
  • Wiggle tests while monitoring live data to check for intermittent wiring faults

Signal parameters

  • Reference (sensor supply) voltage: typically ~5.0 V (verify vehicle-specific spec)
  • Signal output typical range: ~0.5–4.5 V depending on design; high fault commonly seen >4.5–4.8 V
  • Ground resistance: should be very low (
  • If pulse-type sensor, expect a varying waveform when pump/air flow is active (use scope if available)
  • No signal or a constant rail voltage on the signal wire indicates open/short condition

Diagnostic algorithm

  1. Connect a scan tool and record live data and freeze-frame. Confirm P2438 is current and note conditions.
  2. Visually inspect the bank 2 air flow/pressure sensor, connector, and wiring for obvious damage, corrosion, or contamination.
  3. With ignition ON (engine OFF), backprobe the sensor connector: verify reference voltage (≈5 V), sensor ground, and signal voltage. Compare to bank 1 if possible.
  4. If signal reads high at key ON/engine OFF, disconnect the sensor and recheck the signal line at the harness. If signal drops when sensor disconnected, suspect wiring/ECM; if signal still high, likely short to V+ in harness or PCM output stuck.
  5. Check continuity between the sensor ground and battery negative; repair poor grounds.
  6. Inspect and test for a short to battery voltage on the signal wire (measure voltage between signal wire and ground with sensor disconnected).
  7. If wiring and connector test good, bench-test or replace the sensor and clear codes. Re-test and monitor live data during operation.
  8. If new sensor does not correct the condition and wiring checks normal, suspect PCM fault and verify with manufacturer-specific diagnostics before replacement.
  9. After repairs, clear codes and perform a complete verification drive cycle to ensure the code does not return.

Likely causes

  • Failed or electrically shorted air flow/pressure sensor (bank 2)
  • Short to battery voltage on the sensor signal wire or sensor supply circuit
  • Poor ground or corroded connector at the sensor
  • Wiring harness damage (pinched, chafed) near the sensor location

Fault status

⚠️ Status
PCM detected an abnormally high voltage/signal on the Air Flow/Pressure Sensor circuit for Bank 2. The condition exceeded allowed limits and set DTC P2438; MIL may be illuminated.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-2.5 hours

Similar codes

P2436 P2435 P2437 P0103 P0496
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