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DTC codes / Chrysler codes / P1121

P1121 · ChryslerTP Sensor Circuit Intermittent High Voltage

P1121 on a Chrysler vehicle means the powertrain control module (PCM) has detected an intermittent high-voltage condition on the throttle position (TP) sensor circuit. The PCM monitors the TP sensor signal and sees it spike above the normal range for a brief moment, then return, which is why it is stored as intermittent rather than a hard fault.

SystemPowertrain
Code typeChrysler specific
SeverityMedium
Fix difficultyIntermediate
AreaFuel and air metering

Symptoms you may notice

  • The check engine light (malfunction indicator lamp) is illuminated, often with no other noticeable symptoms.
  • The engine may stumble or hesitate briefly during acceleration when the intermittent high-voltage signal occurs.
  • The transmission may shift harshly or at the wrong time because the PCM uses throttle position for shift scheduling.
  • A momentary loss of power or a surge may be felt, especially when the throttle is held steady.
  • In some cases, the engine may enter limp-home mode and limit speed or RPM.
  • The cruise control may disengage unexpectedly if the PCM sees an invalid throttle signal.

Common causes, most likely first

  1. A worn or dirty throttle position sensor that produces intermittent high-voltage spikes as the wiper moves across the resistive track.
  2. Corroded, loose, or damaged terminals in the TP sensor connector or the PCM connector.
  3. A chafed or broken wire in the TP sensor signal circuit that intermittently shorts to a higher voltage source.
  4. A faulty ground connection for the TP sensor, causing the signal voltage to float high intermittently.
  5. A failing PCM that misinterprets a normal signal, though this is less common than sensor or wiring issues.
  6. Aftermarket accessories or poor electrical repairs that introduce voltage spikes into the 5-volt reference circuit.

How to diagnose and fix it

  1. Connect a scan tool and check for stored and pending codes, then view live throttle position data while wiggling the TP sensor connector and harness to see if the voltage spikes.
  2. Inspect the TP sensor connector and wiring for corrosion, loose pins, or chafing, and repair any damaged terminals or wires.
  3. Back-probe the TP sensor signal wire at the PCM and monitor voltage with a multimeter while moving the throttle by hand; look for glitches above the normal 0.5–4.5 volt range.
  4. Check the 5-volt reference and ground circuits at the TP sensor for intermittent opens or shorts using a multimeter and a wiring diagram.
  5. If the sensor signal is erratic only at certain throttle positions, replace the throttle position sensor with a quality part and clear the code.
  6. After repairs, clear the codes and perform a road test with the scan tool recording TP sensor data to confirm the intermittent high voltage is gone.
  7. If the problem persists after sensor and wiring repairs, suspect the PCM and perform pinpoint tests according to Chrysler service information before replacement.

Intermittent TP Sensor High Voltage Traps

  • A common mistake is replacing the TP sensor without checking the connector and harness first; a loose ground or chafed wire can mimic a failing sensor and the new part will not fix the code.
  • The code can set from a momentary voltage spike that lasts only milliseconds, so a static multimeter check may look perfect while a lab scope or scan tool with graphing capability is needed to catch the glitch.
  • On many Chrysler vehicles, the TP sensor shares a 5-volt reference with other sensors; a short in another sensor's circuit can pull the reference high and set P1121 even though the TP sensor itself is fine.
  • A dirty throttle body or carbon buildup can cause the throttle plate to stick slightly, making the TP sensor wiper move erratically and produce intermittent high-voltage signals that look like an electrical fault.
  • P1121 is often stored alongside codes for other throttle-related circuits, so always diagnose the root cause rather than treating each code as a separate sensor failure.

Can I keep driving with P1121?

You can usually drive the vehicle short distances to a repair shop, but avoid aggressive acceleration or sustained high speeds because an intermittent throttle signal can cause sudden hesitation or limp-home mode. If the engine repeatedly stumbles or the vehicle enters limp mode, stop driving and have it towed to prevent a dangerous loss of power.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for Chrysler vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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