OBD-II trouble code
U043D: Invalid Data Received From Accelerator Pedal Module
A module — usually the engine computer — is receiving messages from the accelerator pedal module, but the throttle-demand data inside them is implausible or out of range. The link is alive; the content is wrong. The vehicle may drop into a reduced-power fail-safe.
Quick facts
- System
- Network
- Category
- Network Communication
- Severity
- Medium severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $100 – $600
- DIY difficulty
- Shop recommended
Browse every code in U0401–U0478, or start from the full code library.
What does U043D mean?
On a modern drive-by-wire vehicle there is no cable between the gas pedal and the throttle. Instead, the accelerator pedal module — the assembly that houses the accelerator pedal position (APP) sensors — measures how far the driver is pressing and broadcasts that demand onto the vehicle network. The engine control module (ECM) reads it and opens the electronic throttle accordingly. U043D sets when a receiving module is still hearing from the accelerator pedal module, but the pedal-position data in its messages is invalid: a value is out of range, implausible, or disagrees with the redundant channel the system expects. The link is alive — the content can't be trusted. That is the key difference from a lost-communication code, which means the pedal module has gone completely silent.
Accelerator pedal assemblies are built with redundancy — typically two independent sensor signals that must track each other in a fixed relationship — precisely because throttle demand is safety-relevant. When the two signals disagree, or one reports a physically impossible value, the ECM cannot know how hard the driver actually wants to accelerate, so it rejects the data and sets U043D. Because throttle demand is safety-critical, many vehicles respond by dropping into a reduced-power 'limp' mode: throttle response is deliberately blunted, the engine may be capped at a low RPM or idle, and cruise control is disabled until the fault clears. The vehicle usually still moves under its own power, but acceleration can be sluggish or unresponsive, which is why this code deserves prompt attention even though it is officially a data-integrity fault rather than a wiring fault.
The causes cluster around whatever makes the pedal module report bad numbers. A worn or contaminated APP sensor, a damaged or corroded pedal connector, chafed signal wiring, or low system voltage can all corrupt the values in transit or at the source. Software that is outdated or was never re-flashed after a pedal-assembly or ECM replacement can also throw the code. Because U043D is frequently accompanied by a specific pedal-position code — such as a P2122/P2127-style APP circuit fault — read the full list first: a companion powertrain code often names the exact sensor or circuit at fault, and low voltage is worth ruling out early because it is a common, inexpensive trigger.
Common causes
- Damaged, loose, or corroded connector at the accelerator pedal module
- Low system voltage or a poor ground destabilizing the sensor readings
- Worn, contaminated, or failing accelerator pedal position (APP) sensor
- Chafed or shorted pedal signal wiring corrupting the values in transit
- Outdated or mismatched software after a pedal-assembly or ECM replacement
- Electrical noise on the bus corrupting messages
- Internal fault within the accelerator pedal module
Symptoms
- Check engine light on, often with a reduced-power warning
- Reduced-power or 'limp' mode — sluggish or capped acceleration
- Hesitation or unresponsive throttle when pressing the pedal
- Cruise control disabled
- Companion accelerator-pedal-position codes (P2122/P2127-style) stored alongside U043D
Diagnostic steps
- 1.Read ALL stored codes first — U043D is often accompanied by a specific APP circuit code that names the real fault.
- 2.Load-test the battery and check charging voltage and grounds; low voltage is a common, cheap trigger.
- 3.Inspect the accelerator pedal connector and wiring for corrosion, looseness, chafing, and moisture.
- 4.Sweep the pedal by hand with the ignition on and the ENGINE OFF while watching both APP signals in live data. They should track each other in a fixed ratio through the whole travel, and a dropout or a step in either one as the pedal moves is the fault. Do not do this with the engine running: you are under the dash, out of the seat, and the throttle will open with nobody at the wheel.
- 5.Check the reference and the ground rather than voltage-dropping the signal wires. An APP signal feeds a high-impedance module input and carries almost no current, so a voltage-drop test on it reads nothing and passes the exact resistance it is hunting for. Instead, with the connector mated and the key on, measure the sensor's 5V reference against specification and measure the sensor ground against battery negative — the reference and ground are what scale the signal, so a sagging reference or a ground offset of more than a couple of hundred millivolts shifts both channels and is the fault that makes two good sensors disagree.
- 6.Wiggle-test the pedal harness and flex the connector while the live data is on screen. An intermittent in a signal circuit shows up as a glitch in the trace, which is the only way an almost-no-current circuit will reveal a bad crimp.
- 7.Verify the pedal module and ECM have the correct, current software, especially after any recent parts replacement.
- 8.Address any companion pedal-position code before condemning the pedal module itself.
Repair cost
$100 – $600
Cost depends on the source of the bad data. Correcting low voltage, a weak battery, or a bad ground is often $150-$400. Repairing a corroded connector or chafed pedal wiring varies with access. An accelerator pedal assembly (which includes the APP sensor) is typically $150-$450 installed on most vehicles. A software re-flash is $100-$200. Diagnose before replacing — a companion pedal code and a voltage check usually point straight at the cause.
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DIY vs shop
Leave this one to a qualified shop. The barrier here is module programming, security access, and bus-level diagnosis that need manufacturer-grade scan tools and the credentials to use them. DIY attempts often produce a more expensive problem than the original code.