When you see a P0112 code pop up, it means your car’s computer-what we call the PCM-thinks the air coming into your engine is much hotter than it really is. From my time under the hood, I can tell you the intake air temperature (IAT) sensor is what’s responsible for keeping tabs on how warm or cool that air actually is. The computer relies on this info to get fueling and timing just right. If the sensor sends back a reading that's way out of whack-like showing 300 degrees even though the engine's stone cold-the PCM throws the P0112 to let you know something's fishy. Basically, the IAT sensor works by changing resistance as the temperature shifts, and the computer reads those signals. This setup helps with emissions and keeps your engine running smooth. But if that sensor or its wiring goes bad, all those calculations go haywire.
DTC P0112
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6 minutes of readingCauses of P0112 trouble code
From experience, the most common reason I see for a p0112 code is a faulty IAT sensor itself-sometimes the sensor shorts out internally or just fails with age. But there are a few other things that can trigger this code, and it's important not to overlook them. Here’s what I usually find:
- Defective IAT sensor (internal short, open circuit, or physical damage)
- No reference voltage reaching the sensor due to a broken wire
- Short to ground in the IAT signal circuit
- Damaged or corroded IAT connector
- PCM (engine computer) malfunction, though this is rare
- Excessively high intake air temperatures (unusual, but possible if the air duct is routed poorly or the car is overheating)
In cases like this, it’s usually the sensor or its wiring, but I always check the whole system just to be sure.
Symptoms of obd code P0112
Honestly, you might not notice much when this code pops up, except for the check engine light coming on. Sometimes, you’ll feel the engine running a bit rough, or you might notice it pings or knocks under load-especially if the air/fuel mixture isn’t right. In some cases, emissions can go up, and if you need to pass a smog test, this could cause you to fail. But for most folks, the main clue is that warning light staring back at you from the dash.
Diagnosis steps for P0112 code
Here’s how I go about diagnosing a obd p0112, step by step. I always recommend starting with the basics before diving into anything complicated:
- First, I plug in a scan tool and check the IAT reading with the engine cold. The IAT value should be close to the outside air temperature or match the coolant temp if the car’s been sitting overnight.
- If the reading is way too high, I visually inspect the IAT sensor and its connector for any obvious damage, corrosion, or loose pins. Don’t forget to check the wiring harness for any signs of rubbing or cuts.
- Next, I disconnect the IAT sensor and see what the scan tool shows. If the reading drops to a very low temperature (like -20°F or -30°C), that usually means the sensor is bad and needs replacing.
- If the reading stays high even with the sensor unplugged, I check the wiring between the sensor and the PCM for shorts to ground or broken wires. A multimeter is your friend here-test for continuity and resistance between the harness terminals.
- If all the wiring checks out but the code remains, I start to suspect the PCM itself, but honestly, that’s the last thing to fail. It’s better to have someone assist you with these checks, especially when probing wires.
Make sure to inspect everything carefully before moving on to replacing parts. It’s best to start with something simple.
Common mistakes when fixing P0112
I’ve seen plenty of folks jump straight to replacing the IAT sensor without checking the wiring or connector first. That’s a surefire way to waste money if the real problem is a broken wire or corroded plug. Another common mistake is not comparing the IAT reading to the coolant temp when the engine is cold-this quick check can save a lot of time. And don’t forget to check for other codes that might point to a bigger wiring or PCM issue. Skipping these steps can lead to chasing your tail and missing the real fix.
Seriousness of dtc P0112
This isn’t something you want to ignore. While it might not leave you stranded, a faulty IAT sensor can cause your engine to run poorly, increase emissions, and even lead to engine knocking or pinging, especially under load. Over time, running with the wrong air/fuel mixture can damage your catalytic converter or, in rare cases, cause internal engine damage. You don’t want this kind of trouble on the road-things can go south quickly if overlooked. Don’t put this off for later.
Repair solutions for obd2 code P0112
Here’s what usually solves the problem, based on what I see in the shop and what the official procedures recommend:
- Replace the IAT sensor if it’s faulty or reading incorrectly
- Repair or replace any damaged wiring or connectors in the IAT circuit
- Fix any short to ground or open circuit in the wiring harness
- In rare cases, replace the PCM if all other components test good and the problem persists
- Make sure the intake air ducting is intact and not pulling in hot air from the engine bay
After repairs, always clear the code and verify the fix with a scan tool.
Conclusion
To sum it up, P0112 means your engine’s computer thinks the incoming air is way hotter than it should be, usually because of a bad IAT sensor or wiring issue. It’s not the most dramatic code, but it can lead to bigger problems if ignored. I recommend starting with a careful inspection and some simple tests before replacing anything. The most reliable fix is usually a new sensor or repairing the wiring, but don’t skip the basics. Take care of it promptly to avoid headaches down the road and keep your engine running right.
