What is code P0108 on Dodge Grand Caravan?
The code P0108 on a Dodge Grand Caravan indicates a fault in the MAP (manifold absolute pressure) or barometric pressure sensor circuit, specifically a reading that is higher than the PCM expects. In plain terms, the engine computer is seeing an abnormally high pressure signal from the MAP/BAR sensor and flags a fault.
This code can affect engine performance, idle stability, and fuel economy, and it often points to a problem in the sensor itself, the wiring, or related intake system components. While the Grand Caravan uses MAP and barometric signals to help manage fuel delivery and timing, a P0108 means the sensor circuit is sending the PCM an unexpectedly high voltage or pressure reading, prompting a fault code to illuminate the check engine light.
What the MAP/Barometric Pressure Sensor does
The MAP sensor measures the pressure inside the intake manifold, providing data the engine computer uses to calculate air density, fuel quantity, and ignition timing. Some Chrysler/FCA configurations also rely on a barometric (BARO) sensor to help gauge ambient air pressure for altitude adjustments. Together, these sensors help the PCM adjust engine performance across different driving conditions.
MAP sensor location
On many Grand Caravan models, the MAP sensor is mounted on or near the intake manifold or throttle body. In some configurations, the MAP and barometric sensor signals are handled by the same unit or integrated into the intake manifold assembly. If you’re replacing the sensor yourself, consult your vehicle’s service manual for the exact location to avoid confusion with nearby vacuum ports.
Common symptoms you might notice with P0108
Encountering code P0108 can show up in a variety of ways, depending on how the high MAP signal influences the PCM’s calculations. Below are typical signs owners report.
- Check Engine Light (CEL) or Service light illuminated.
- Rough idle or stalling at stops.
- Poor acceleration or reduced engine power.
- Degraded fuel economy or unusual engine behavior under load.
- Engine misfire symptoms or hesitation during acceleration.
If you notice any combination of these symptoms along with a P0108 code, it’s advisable to perform a focused diagnostic check rather than driving long distances, as incorrect air/fuel calculations can stress the engine over time.
Common causes of P0108 on a Dodge Grand Caravan
While the exact cause can vary by year and engine, several issues frequently lead to a P0108 diagnosis on Grand Caravans.
- Faulty MAP sensor or BARO sensor that is stuck high or providing an erroneous signal.
- Vacuum leaks or intake manifold leaks that alter sensed pressure or create inconsistent readings.
- Oil, dirt, or contamination on the MAP sensor that skews readings, or a sensor that has become damaged from heat exposure.
- PCM (engine control module) fault or communication issue with the MAP/BAR signal.
These causes are common across many vehicles, but the Grand Caravan’s layout with multiple engines (for example, 3.3L, 3.8L, and later 3.6L Pentastar variants) means the exact sensor location and wiring can vary slightly by year and model.
How to diagnose and fix P0108 on a Grand Caravan
Diagnosing P0108 involves verifying the sensor signal, inspecting wiring, and ruling out leaks or contaminants. The steps below outline a practical approach you or a technician can follow.
- Use an OBD-II scanner to confirm P0108 and check freeze frame data for MAP sensor readings at idle and under load.
- Inspect the MAP/barometer sensor and its mounting area for signs of damage, oil contamination, or physical obstruction.
- Check the wiring harness and connectors to the MAP/BAR sensor for corrosion, bent pins, or loose connections; repair or replace as needed.
- Test the MAP sensor with a multimeter (or swap with a known-good unit) to compare voltage output across engine conditions. Expect a voltage range consistent with the vehicle’s service specs (often around a low voltage at idle and rising with RPM/less vacuum). Do not rely on rough guesses; refer to the service manual for exact values.
- Inspect for vacuum leaks around the intake, throttle body, vacuum hoses, and gasket areas, as unmetered air can influence MAP readings.
- Check for signs of oil or dirt on the sensor; clean or replace the sensor if contamination is present.
- If the sensor and wiring check out, consider replacing the MAP/BAR sensor as a relatively inexpensive and common fix. If the new sensor still reports high readings, investigate the PCM and its wiring more deeply or consult a dealer for calibration concerns.
After addressing the suspected causes, clear the codes and perform a sustained road test to confirm the fault does not reappear. If the code returns, a deeper diagnostic may be required to assess PCM integrity or other related sensors.
What to do next
For most owners, starting with a sensor and wiring check is the most cost-effective path. If you’re not comfortable performing electrical diagnostics or sensor testing, a qualified technician can diagnose, replace the MAP/BAR sensor, and test the system to ensure there are no lurking vacuum leaks or PCM issues.
Summary
Code P0108 on a Dodge Grand Caravan signals a MAP/Barometric pressure sensor circuit issue with readings higher than expected. The issue is most commonly caused by a faulty MAP sensor, wiring/connectivity problems, or vacuum leaks, though PCM-related faults are also possible. A methodical approach—inspect and test the sensor, check wiring and vacuum leaks, clean or replace the sensor if needed, and verify by road testing—will help determine the exact cause and restore proper engine performance.
In short, P0108 is a signal-quality fault in the MAP/BAR sensor circuit, and addressing it promptly can prevent longer-term engine performance problems and fuel economy loss.
