P0122 is a code I’ve run into more times than I can count, and it basically means your car’s brain-what we call the PCM-is seeing a signal from the Throttle Position Sensor (TPS) “A” circuit that’s lower than it should be. Let me break it down for you: the TPS is the sensor that lets the computer know exactly how far you’re pressing the gas pedal. Most of the time, you’ll find it mounted right on the throttle body, but on some of the newer, drive-by-wire setups, it’s built into the pedal assembly. The engine computer relies on this info for everything from mixing fuel and air, to timing spark, to managing emissions. Now, if the voltage drops too low, the computer doesn’t trust what it’s hearing from the sensor. That’s when you’ll get the P0122 code and that dreaded Check Engine Light on your dash.
DTC P0122
6106
6 minutes of readingCauses of P0122 trouble code
From my time under the hood, I can tell you that when it comes to eobd dtc p0122, there are a few usual troublemakers. Nine times out of ten, it’s either a worn-out sensor or an issue with the wiring. Here’s what I see show up most often in my shop:
- A throttle position sensor that’s gone bad or just worn down from years of use
- A sensor that isn’t mounted tight or has slipped out of adjustment
- A wiring harness with a short to ground, a broken wire, or a connector that’s gotten crusty with corrosion
- A throttle position switch that’s acting up
- Problems with the electronic throttle pedal on the newer models
- Once in a blue moon, the PCM itself is the culprit
Here’s a pro-tip from the garage: start by checking the sensor and its wiring. That’s where the vast majority of these headaches begin.
Symptoms of P0122
When this code shows up, you’ll know something isn’t right with how your ride is running. Here’s what I’ve seen drivers complain about in the shop:
- The Check Engine Light makes an appearance
- Hard starting, especially on chilly mornings
- The engine hesitates or gives a little stumble when you try to accelerate
- Idle that’s rough, too low, or, every so often, sky-high for no good reason
- Stalling-usually at stoplights or when you’re coming to a halt
- Surging or jerking as you’re driving along
- Little to no response when you step on the gas
If you’re noticing any of this, don’t brush it off. Things can go downhill fast if you let it slide. I’ve seen this pop up on plenty of Hondas, GMs, and Chevrolets too, so no brand is immune.
Diagnosis steps for obd2 code P0122
When I’m tackling a gm dtc p0122, here’s how I break down the diagnosis:
- First thing, I grab the scan tool and pull the codes-not just P0122, but any buddies like P0120, P0121, P0123, or P0124. Sometimes those extra codes are the real clue.
- Next, I get my eyes on the TPS and its wiring. I’m looking for connectors that aren’t tight, wires that look chewed up, or any sign of corrosion. Check both at the sensor and, if it’s a newer car, at the pedal assembly too.
- With the key on and engine off, I grab my multimeter. You want to see about 5 volts at the reference wire and a good ground at the connector. If you’re missing one, you’ve got a wiring or PCM problem to chase.
- Then, I check the TPS signal itself. At idle, it should be at about 0.5 to 1 volt. As you slowly open the throttle, that should climb smooth as silk up to around 4.5 volts when it’s wide open. If it stays low or jumps around, the sensor’s toast.
- If everything checks out with the sensor and wiring, then-only then-do I start looking at the PCM. But honestly, that’s not where the trouble usually lies.
Here’s a tip: get a buddy to work the pedal while you watch the readings. It makes the job a lot easier. And whatever you do, don’t skip a thorough look at the wiring before you start swapping parts.
Common Mistakes with P0122 code
A classic mistake I see: folks rush to replace the throttle position sensor without even glancing at the wiring or connectors. If there’s a broken wire or a crusty terminal, you’re just throwing money away by swapping sensors. Another slip-up? Ignoring related codes-sometimes the real issue is at the pedal sensor or even buried in the PCM. Here’s my advice: always check basics first. Make sure that sensor’s getting power and ground before you toss it. I’ve lost count of how many dtc p0122 chevrolet repairs have turned into a wild goose chase because someone skipped a simple wiring check.
Seriousness of dtc P0122
I can’t stress this enough: this isn’t a code you want to push off till next week. A bad TPS or a wiring fault can leave your car stalling without warning, hesitating when you’re trying to merge, or just plain refusing to move when you need it to. Frankly, it’s a safety hazard, especially if you’re in heavy traffic or cruising down the interstate. Ignore it long enough, and you could toast your catalytic converter or wind up stranded somewhere. It’s not worth the risk.
Repair options for obd code P0122
When it comes to fixing this, here’s what’s worked best for me over the years:
- Swap out the throttle position sensor if it’s shot or worn out
- Patch up or replace any damaged wiring or crusty connectors
- Clean up corroded terminals and double-check that every connection is snug
- Adjust the sensor if it’s one of the types that lets you tweak its position
- If you’re working on something newer and the pedal assembly’s at fault, you’ll probably need to replace the whole pedal
- And in those rare cases, if the PCM’s the problem, you might have to repair or replace it
Don’t forget to clear the code and take the car for a spin to make sure everything’s really fixed and the code doesn’t come back to haunt you.
Conclusion
Bottom line: P0122 means your engine computer isn’t getting the right signal from the throttle position sensor, and that’s nothing to take lightly. It can seriously throw off how your car drives, and it’s a real risk for stalling or hesitation out on the road. The smart move? Start with a thorough look at the sensor and wiring, fix what you find, and only swap parts if you’re sure they’re bad. Don’t sleep on this one-get it sorted before it turns into a bigger headache.
