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DTC codes / Chrysler codes / P1108

P1108 · ChryslerBARO To MAP Sensor Circuit Comparison Too High

P1108 on a Chrysler vehicle means the powertrain control module (PCM) compared the barometric pressure (BARO) signal against the manifold absolute pressure (MAP) signal and found the BARO reading too high relative to the MAP reading. The PCM expects these two pressure sensors to track within a calibrated window, especially when the ignition is on and the engine is not running, so a persistent spread beyond that window sets this code.

SystemPowertrain
Code typeChrysler specific
SeverityMedium
Fix difficultyIntermediate
AreaFuel and air metering

Symptoms you may notice

  • Malfunction indicator lamp (MIL) illuminated, often with no other noticeable symptoms
  • Rough idle or unstable idle quality, particularly after a cold start
  • Hesitation or stumble during light acceleration
  • Poor fuel economy or a rich-running exhaust smell
  • Elevated or erratic idle speed as the PCM compensates for skewed pressure data
  • In some cases, no drivability complaint at all and only the stored code is found during a scan

Common causes, most likely first

  1. Contaminated or failed MAP sensor on the intake manifold
  2. Failed BARO sensor, which on many Chrysler applications is integrated into the PCM
  3. Vacuum leak or restricted vacuum supply to the MAP sensor
  4. Wiring fault, corrosion, or poor terminal tension in the MAP sensor circuit
  5. PCM internal fault affecting the BARO reference or comparison logic
  6. Intake manifold or throttle body leak altering MAP readings at key-on
  7. Aftermarket air intake or modified intake plumbing that changes MAP sensor behavior

How to diagnose and fix it

  1. Scan all modules and record freeze-frame data for P1108, then clear the code and verify whether it returns after a key-on, engine-off cycle
  2. Compare live BARO and MAP readings with the key on and engine off; they should be nearly equal at your altitude, so a large spread confirms the fault
  3. Inspect the MAP sensor connector and harness for corrosion, chafing, and loose terminals, and check vacuum hoses for cracks or disconnection
  4. Test the MAP sensor signal and reference voltage with a multimeter or scan tool against Chrysler specifications
  5. Check for intake vacuum leaks using a smoke test or carburetor cleaner around the manifold and throttle body
  6. If the MAP sensor and wiring test good, evaluate the BARO sensor or PCM, since BARO is often internal to the PCM on Chrysler vehicles
  7. After repair, clear codes and perform a road test with several key cycles to confirm the comparison stays within range

Why BARO and MAP must agree at key-on

  • The PCM performs the BARO-to-MAP comparison most reliably with the ignition on and the engine off, so a code that sets only after startup often points to a vacuum leak rather than a failed sensor.
  • On many Chrysler vehicles the BARO sensor is not a separate serviceable part but is integrated into the PCM, so technicians who replace the MAP sensor first sometimes still face the code.
  • A dirty or oil-fouled MAP sensor from an over-oiled aftermarket air filter can skew readings enough to set P1108 without any hard failure.
  • Altitude changes affect both sensors equally, so a genuine BARO-to-MAP mismatch is not caused by driving at elevation and should not be dismissed as normal.
  • This code is frequently misdiagnosed as a simple MAP sensor failure when the real problem is a small intake leak that only shows up at idle vacuum levels.

Can I keep driving with P1108?

The vehicle is generally safe to drive to a repair shop because the PCM uses the MAP signal for fuel control and the fault usually causes only mild drivability issues. Avoid heavy acceleration and long trips until the cause is found, since a rich condition can damage the catalytic converter over time.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for Chrysler vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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