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The smooth operation of an engine partly depends on achieving the proper air-to-fuel ratio and ignition timing. The ECM (Engine Control Module) calculates both by using information relayed by different sensors such as those installed in the air intake, fuel injection, engine, and exhaust systems.

The Manifold Absolute Pressure/Barometric Pressure (MAP/BARO) sensor circuit relays constant pressure difference information to the ECM. It measures the pressure inside the intake manifold, as well as the barometric/atmospheric pressure in relation to the vehicle. When the ECM detects a problem with the signal sent by this device, an OBD-II P0108 code may be logged by onboard diagnostics.

Mechanic with a diagnostic code scanner
Code P0108 may get triggered if the ECM receives a signal from the MAP/BARO sensor circuit that is above the normal range.

What Does the P0108 Code Mean?

Diagnostic trouble code (DTC) P0108 code stands for “Manifold Absolute Pressure/Barometric Pressure High.” It is triggered by the ECM when it receives a signal from the MAP/BARO sensor circuit that is above the normal range.

Typically, the MAP/BARO sensor is supplied with regulated volts by the ECM on a 5-volt reference circuit. The latter also supplies a ground on a low reference circuit. As engine load and operating conditions vary, the MAP/BARO sensor relays a signal voltage to the ECM that is relative to any pressure changes.

Vehicles that are prone to code p0108 include various models of Honda (especially Honda Accord), Dodge, Ford, Jeep, and Chevrolet.

 What are the Possible Causes of the P0108 Code?

–           Defective MAP/BARO sensor

–           Faulty, corroded, or loose MAP/BARO sensor circuit wiring or connections

–           Restricted vacuum source for the MAP/BARO sensor

–           Defective, damaged, or clogged catalytic converter(s)

–           In rare cases, a malfunctioning ECM

What are the Common Symptoms of the P0108 Code?

Illuminated Check Engine Light

There are plenty of error codes that may switch on the check engine light. To confirm that it has been triggered by a MAP/BARO sensor circuit malfunction, you’ll need to connect an OBD-II scan tool to your vehicle’s OBD port.

Reduced fuel economy

An issue with the MAP sensor can throw off your car’s air/fuel ratio, leading to increased fuel consumption. 

catalytic converter of a modern car
A possible cause of error code P0108 is a defective, damaged, or clogged catalytic converter.

Poor engine performance

A malfunction in the MAP/BARO sensor circuit may also affect the drivability of your vehicle. Your car may become hard to start, hesitate during acceleration, stall unpredictably, or experience rough idling.

How to Diagnose the P0108 Code

Now that you know what causes a P0108 code as well as its symptoms, the next step is identifying which issue triggered the code. Don’t hesitate to take your vehicle to a professional if you’re unsure about performing the diagnosis.

If you’re an experienced DIY-er looking for advice on testing and fixing this trouble code yourself, here are some videos that may give you a better idea of what the troubleshooting process might involve: 

How to Fix the P0108 Code

The P0108 code is a generic DTC, which means it’s supported by various makes and models. While most vehicles will experience similar symptoms, the steps for diagnosis and repair may be different between vehicle models.

If you’re unsure about having enough technical knowledge to fix the code yourself, it’s best to bring your vehicle to the nearest auto repair shop to have it fixed by an expert. If you decide on doing it on your own, repair manuals (like those from Chilton) and an ALLDATA vehicle subscription are great resources for factory repair information.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic.

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