When you see a P0108 code pop up, your vehicle’s computer-whether it’s the ECM or PCM-is picking up a signal from the Manifold Absolute Pressure (MAP) or Barometric Pressure (BARO) sensor that’s higher than what it should be. Let me break that down for you: that MAP or BARO sensor is what tells your engine how much pressure is inside the intake manifold compared to the outside air. The computer uses this data to decide how much fuel should go in and when to fire the spark, so the engine stays smooth and efficient. If that sensor starts sending a signal that’s too high, the computer gets thrown off and can’t balance your air-fuel mixture like it should. I’ve seen this sensor play a huge role in ‘speed density’ fuel injection systems, but plenty of cars with Mass Airflow (MAF) sensors also rely on a MAP sensor for backup or fine-tuning. Bottom line: if you get this code, your engine’s not getting the right pressure info, and everything from performance to fuel economy can take a hit.
DTC P0108
4799
6 minutes of readingCauses of High Manifold Pressure Signal with P0108
Over the years, I’ve found that the number one culprit behind a p0108 code is a MAP or BARO sensor that’s just given up the ghost. These things wear out, plain and simple. But don’t stop there-wiring and connectors are often the unsung troublemakers. I can’t count how many times I’ve chased a ghost only to find a corroded pin or a loose plug. Vacuum lines are another classic source of headaches; a cracked, clogged, or totally disconnected vacuum hose can easily throw off sensor readings. Every so often, a clogged or busted catalytic converter builds up backpressure, tricking the sensor into sending bad info. And although it doesn’t happen much, the ECM itself can act up. Here’s what I always dig into first:
- MAP/BARO sensor that’s failed
- Worn, corroded, or loose wiring/connectors at the sensor
- Vacuum supply to the sensor that’s restricted or disconnected
- Clogged or damaged catalytic converter(s)
- ECM malfunction (not common, but worth a look if all else fails)
Symptoms Linked to dtc P0108
The first thing you’ll likely notice is that dreaded Check Engine Light glaring at you. But that’s just the tip of the iceberg. From what I’ve seen, engines with this code don’t like to start, might idle all lumpy, and sometimes even stall out in the middle of traffic. Acceleration turns sluggish, and you’ll probably watch your fuel gauge drop faster than usual. Sometimes, you’ll feel hesitation or a stumble when you put your foot down. If you’re seeing these symptoms-especially if you drive a Honda, Chrysler, Ford, Renault, or any car throwing a dtc p0108 honda or chrysler dtc p0108-chances are this code’s at the root of your troubles.
Diagnosis Process for P0108 Engine Code
Here’s how I tackle a P0108 diagnosis in the shop. First, I open the hood and give the MAP/BARO sensor and its wiring a close look-any signs of cracks, corrosion, or a loose connector? I’ll gently wiggle the connector, because sometimes a bad connection is all it takes to set this code. Next, I check the vacuum line (if your system uses one). Is it brittle, split, or not even hooked up? That’s an easy fix if you catch it. If everything checks out visually, I grab my scan tool and pull up live MAP data. With the key on, engine off, the sensor should read right around atmospheric pressure-roughly 14.7 psi at sea level. If it’s way off, that’s your first clue. Once the engine’s running, manifold pressure should drop thanks to vacuum. If you see no change or the reading’s stuck high, I’ll backprobe the sensor’s signal wire with a multimeter (or check signal frequency if I’m working on certain Fords). If the sensor looks good, I’ll check for a plugged exhaust by measuring backpressure-if the cat’s clogged, it’ll show up here. Only after ruling out the basics do I start thinking about a possible ECM problem, and honestly, that’s pretty rare. Always start simple-you’d be amazed how often a quick visual inspection finds the problem.
Common Mistakes When Fixing obd code P0108
A classic mistake I see all the time: folks jump right to swapping out the MAP sensor without giving the wiring or vacuum lines a second look. It’s easy to miss a tiny crack in a hose or some green gunk in a connector, but those little things can cause big headaches. Skipping the check for a clogged catalytic converter is another trap-if you don’t check for exhaust restrictions, you might miss the real issue and waste money on sensors that were fine all along. And please, don’t just clear the code and hope for the best. If you don’t fix the root cause, it’s only a matter of time before the code comes right back. Go slow, check each piece, and you’ll save yourself a lot of frustration (and cash) down the line.
Seriousness of P0108 Trouble Code
Let me be straight with you-ignoring P0108 is asking for trouble. When the MAP/BARO sensor isn’t playing nice, your engine might run way too rich or too lean, which isn’t just bad for performance-it’ll start eating up fuel and might even wreck important parts. I’ve seen folks ruin their catalytic converters or foul up spark plugs by letting this go too long. Worst case, you’re left stranded when the engine stalls out or refuses to start altogether. So, if you see EOBD DTC P0108, don’t wait around. It’s a risk to your wallet and your safety.
Repair Steps for P0108 Code
Most of the time, the fix is refreshingly simple. If the MAP/BARO sensor’s had it, swapping it out often solves everything. But-and this is a big one-don’t forget to clean and check that wiring and the connectors. Sometimes a little shot of contact cleaner and making sure everything’s plugged in tight is all you need. If you spot a cracked or loose vacuum hose, replace or reconnect it right away. When a catalytic converter is clogged, you’ll have to install a new one to get pressure readings back to normal. And if, after all these steps, the ECM is the issue (which is rare), you’ll want a pro to handle that. My advice? Always start with the basics-sensor, wiring, vacuum lines-before shelling out for pricier repairs. That’s the best way to tackle dtc p0108 and make sure you’re not back in the shop next week.
Conclusion
So here’s the bottom line: P0108 means your engine isn’t getting the pressure info it needs, and that messes up the whole fuel and ignition system. It’s a top-priority problem because it can snowball into expensive repairs if you ignore it. My best advice? Start with a careful inspection of the MAP/BARO sensor, wiring, and vacuum lines. Only dig deeper if those basics check out. Move fast, work methodically, and you’ll get your car running right again-without risking more damage. Don’t let this one slide-take care of it as soon as you see the code.
