What Does P2128 Mean?
The PCM has detected that the voltage from throttle/pedal position sensor 'E' circuit is above the maximum acceptable threshold. This typically indicates a short to voltage or open circuit condition.
Safety Warning
Vehicle may not accelerate or may enter limp mode with fixed throttle position. Unsafe to drive in traffic.
Common Causes
35%
Open circuit in APP sensor signal wire or ground wire
30%
Failed accelerator pedal position sensor with internal open
20%
Corroded or disconnected APP sensor connector
10%
Short to voltage in signal wire
5%
PCM internal circuit failure
Diagnostic Steps
1
Step 1: With ignition on and APP sensor connected, backprobe sensor signal wire; voltage should be ~0.5-1.0V at rest
2
Step 2: Disconnect APP sensor and measure voltage at harness connector; should drop to near 0V or read 5V reference
3
Step 3: Check continuity of ground circuit from APP sensor to PCM or chassis ground
4
Step 4: Inspect connector terminals for corrosion, bent pins, or poor contact
5
Step 5: Test APP sensor resistance values according to manufacturer specifications
Estimated Repair Cost
$150 - $500
Parts + labor, varies by vehicle and location
The PCM has detected that the voltage from throttle/pedal position sensor 'E' circuit is above the maximum acceptable threshold. This typically indicates a short to voltage or open circuit condition.
The most common cause of P2128 (Throttle/Pedal Position Sensor/Switch "E" Circuit High) is: Open circuit in APP sensor signal wire or ground wire
Typical repair costs for P2128 range from $150 to $500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle may not accelerate or may enter limp mode with fixed throttle position. Unsafe to drive in traffic.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P2128 to identify the root cause.
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Quick Info
Category
Powertrain
System
Electronic Throttle Control
Difficulty
Type
Generic (SAE)
Recommended Tools
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