P1122
HyundaiThrottle Position (TP) Sensor Circuit Intermittent Low Voltage
Medium SeverityThis code means the Throttle Position Sensor signal is cutting out or dropping too low to the engine computer. That'll mess with your engine's power and how it shifts gears.
⚠️ Before You Begin (Safety First)
Engine could cut out on you at any time. Be ready for sudden power loss. Always disconnect the battery before messing with wiring or sensors to avoid a shock or frying something else.
Common Symptoms
- Engine feels weak, like it's lost power.
- Hard to keep a steady speed, feels like it's surging or dragging.
- Rough idle, engine shaking or loping.
- Transmission shifts funny, might be hard or delayed.
- Engine might cut out at low speeds, like when you're stopping.
- Check Engine Light is on, obviously.
Common Causes
- Bad Throttle Position Sensor itself, it's just worn out.
- Loose or corroded wiring to the sensor, or a bad connector.
- A short in the sensor circuit, grounding out the signal.
- A bad connection at the engine computer, which is rare but happens.
- Dirty throttle body causing the throttle plate to stick, messing with the sensor.
Frequently reported on: Hyundai Sonata (2006-2010), Hyundai Elantra (2007-2011), Hyundai Santa Fe (2007-2012), Hyundai Accent (2006-2011)
Diagnostic Steps
- Pop the hood. Find the Throttle Position Sensor, it's usually bolted right to the throttle body on the intake.
- Check the sensor connector. Make sure it's snug and clean. No green crud inside.
- Unplug it. Look for bent pins or corrosion on both the sensor and harness side. Clean it up with electrical cleaner if it looks bad.
- Plug it back in tight. Give it a wiggle to make sure it's seated right.
- Clear the code with a scanner. Take it for a drive, see if the code comes back and how it runs.
- If the code returns and you've checked the wiring, swap out the Throttle Position Sensor. They're usually a couple of screws and a plug, real simple.
👨🔧 When to Call a Professional
If the new sensor don't fix it, or you see obvious damage to the wiring harness, get it to a professional shop. You might have a deeper wiring issue or even a computer problem, and that's not a backyard job.
Commonly Asked Questions
What is a Throttle Position Sensor?
It's a little switch on the throttle body. Tells the computer how far open the throttle plate is, so it knows how much air is coming in. Essential for proper fuel delivery and shifting.
Can I drive with P1122?
You can, but it's gonna run like garbage. Expect rough driving, no power, and weird shifting. Get it fixed, or you'll hate driving it and maybe even cause more issues down the line.
How do I test the TPS?
You need a multimeter. Back probe the signal wire while it's still plugged in. Have someone slowly open the throttle by hand. The voltage should rise smoothly, no drops or spikes. If it's jumpy, it's bad.
Is a dirty throttle body related to P1122?
Sometimes. If the throttle plate sticks or doesn't move smoothly because it's gunked up, it can mess with the sensor's reading. Clean the throttle body first if it's really dirty; it's a cheap fix to try.
Do I need to program a new TPS?
Most of the time, no. Just bolt it on, plug it in, and the computer figures it out. Some might need an idle relearn procedure, but usually the computer adapts after a few drive cycles. Check your service manual to be sure.