P2138: Throttle/Pedal Position Sensor D/E Voltage Correlation
P2138 indicates a correlation error between the throttle position sensor (TPS) and the accelerator pedal position sensor (APP). The powertrain control module (PCM) detects that the voltage signals from sensor D (typically APP sensor 2) and sensor E (typically TPS sensor 2) do not match within a specified range. This can cause the PCM to limit engine power or enter fail-safe mode.
1. Most Common Causes
- Faulty or worn accelerator pedal position (APP) sensor
- Faulty throttle position sensor (TPS)
- Corroded, loose, or damaged wiring or connectors in the sensor circuit
- Short circuit or open circuit between circuits D and E
- Carbon buildup or dirt accumulation in the throttle body
- Internal ECM/PCM failure (less common)
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine power or limp mode
- Poor acceleration or hesitation
- Erratic idle or stalling
3. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Visually inspect wiring and connectors at throttle body and accelerator pedal for damage or corrosion.
Step 3: Use a multimeter to check voltage signals from APP sensor and TPS; compare to manufacturer specs.
Step 4: If signals are out of range, replace the faulty sensor (APP or TPS) and clear codes.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended. The vehicle may enter limp mode, limiting speed and acceleration, which can be dangerous in traffic.
How much does it cost to fix?▼
Typically $50-$150 for parts and labor, but costs can vary depending on the specific sensor and labor rates.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.