P0108: How to Diagnose & Fix — Manifold Absolute Pressure/Barometric Pressure Circuit High Input
2 vehicles · 2 makes · $40-$180 repair
How to diagnose and fix P0108: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Honda Civic · 1996–1999
The manifold absolute pressure (MAP) sensor mounted on the throttle body of 1.6L D16 Civics commonly fails as it ages, losing the ability to hold vacuum or drifting out of its 0.5-4.5V calibration range. Because the PCM uses MAP voltage as the primary load input on these speed-density systems, a failing sensor causes the ECU to mis-fuel and mis-time the engine. Failures often set P0107 / P0108 / P1128 / P1129 codes and frequently coincide with cracked vacuum hoses on the upper intake.
Common Symptoms
- Check engine light with P0107, P0108, P1128 or P1129
- Rough idle and stumbling
- Hesitation and loss of power under load
- Rich-running condition and rotten-egg smell from catalyst
- Hard cold starts and emissions test failure
How to Fix
Verify the vacuum supply hose at the throttle body is not cracked or off, then back-probe the MAP sensor signal wire: at key-on engine-off it should read ~2.8-3.0V (atmospheric), dropping to ~1.0-1.5V at idle. If voltage is stuck high, stuck low, or doesn't track manifold vacuum, replace the MAP sensor (Honda P/N 37830-P05-A01 or equivalent). Clear codes and re-test; persistent codes after replacement usually indicate a vacuum leak.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine Honda 37830-PAA-S00 MAP sensor setOEMHonda 37830-PAA-S00 (replaces 37830-P0G-S00)
MAP sensor replacement after reference, ground, vacuum passage and signal-response tests prove sensor failure Fitment/availability: Honda catalog fitment covers 1996-2000 Civic DX/EX/HX/Si/CX/GX/LX branches and supersedes 37830-P0G-S00. …
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Sources for this issue (3)
Ford Escape · 2013–2013
The engine wiring harness splices that feed the Manifold Absolute Pressure (MAP) sensor were crimped with insufficient compression on 2013 Escapes built January 11, 2012 through April 1, 2013. The loose splice sends an incorrect MAP signal to the powertrain control module, and the PCM responds with hesitation, a rough or unstable idle, or an outright stall — often with no stored code that points at the harness, because the sensor itself tests good. Ford recalled the vehicles under 14S17 (NHTSA 14V495000), then had to re-recall them as 14S17-S1 (NHTSA 15V813000) when the first remedy did not hold, extending coverage to 2013-2014 Focus ST as well. This is an electrical-connection defect and is completely separate from the 1.6L coolant intrusion and cylinder-head cracking issues that dominate this generation, though it affects many of the same cars.
Common Symptoms
- Engine hesitates or bucks under light throttle
- Engine stalls at idle or when coming to a stop
- Rough or hunting idle
- Check engine light with fuel-trim or MAP-related codes, or no code at all
- Symptom is intermittent and worse when the engine is warm
How to Fix
Free recall remedy under NHTSA 15V813000 / Ford 14S17-S1 — the dealer cuts out the original crimped splices and installs new splices in the engine wiring harness at no charge. If the car had the first version of the repair (14S17 / 14V495000) it still needs the 14S17-S1 re-repair, so check the VIN even on a car with a recall already logged. If the stall persists after the splice repair, have the MAP sensor and the harness pigtail load-tested with the engine warm rather than replacing the PCM.
Sources for this issue (3)
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P0108 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0108 mean?
P0108 stands for "Manifold Absolute Pressure/Barometric Pressure Circuit High Input." The PCM detects an abnormally high voltage signal from the MAP/BARO sensor circuit, above the expected range for the engine's operating condition. It often means the sensor reports high manifold pressure when the PCM expects low pressure (such as at idle). Symptoms include reduced fuel economy, poor performance, rough running, and an illuminated check engine light.
What are the most common causes of P0108?
The most common causes of P0108 are: Faulty MAP/BARO sensor, Short to voltage in the MAP signal circuit, Disconnected or leaking vacuum supply to the sensor, Wiring or connector damage at the sensor, Restricted exhaust or clogged catalytic converter raising manifold pressure, Failed PCM (rare). The specific cause varies by vehicle.
How much does it cost to fix P0108?
Repair costs for P0108 range from $40 to $180, depending on the vehicle and root cause.
Which vehicles are affected by P0108?
Au7o has documented P0108 across 2 vehicle models from 2 manufacturers: Ford, Honda.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.