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DTC codes / Honda codes / P1243

P1243 · HondaThrottle Position Insufficient

P1243 on Honda vehicles means the powertrain control module (PCM) has detected that the throttle position sensor signal does not reach the expected value during a commanded throttle movement, indicating insufficient throttle plate travel or a faulty signal. The PCM compares the actual throttle position against the target position during key-on sweep tests and normal driving, and sets this code when the difference exceeds a calibrated threshold.

SystemPowertrain
Code typeHonda specific
SeverityMedium
Fix difficultyIntermediate
AreaFuel and air metering (injector circuits)

Symptoms you may notice

  • Illumination of the check engine light, often with no other noticeable symptoms
  • Reduced engine power or limp mode, where the throttle responds sluggishly or not at all
  • Hesitation or stumble during acceleration from a stop
  • Inconsistent idle speed, sometimes surging or hanging above normal
  • Poor fuel economy or altered shift quality as the PCM compensates for the fault

Common causes, most likely first

  1. Carbon buildup or mechanical binding on the throttle plate or throttle body bore
  2. Faulty throttle position sensor (TPS) or accelerator pedal position sensor (APP) signal
  3. Wiring damage, corrosion, or loose connectors in the TPS or APP circuit
  4. Sticking or failed electronic throttle control (ETC) motor or actuator
  5. PCM software calibration issue or internal PCM fault
  6. Intake air leak downstream of the throttle body affecting throttle position correlation

How to diagnose and fix it

  1. Inspect the throttle body for carbon deposits and clean it with approved throttle body cleaner, then perform a throttle body relearn procedure
  2. Check the TPS and APP sensor connectors for corrosion, loose pins, and chafed wiring; repair as needed
  3. Use a scan tool to monitor throttle position sensor voltage and accelerator pedal position voltage through the full range of motion, looking for dead spots or erratic readings
  4. Perform a key-on engine-off throttle sweep test and compare commanded versus actual throttle position on the scan tool data stream
  5. Check for intake air leaks between the mass airflow sensor and throttle body using a smoke machine or propane enrichment
  6. If the throttle body is mechanically worn or the ETC motor is binding, replace the throttle body assembly and perform the required relearn
  7. Verify PCM calibration is up to date and reflash if a known software update applies, then clear codes and retest

Throttle body carbon is the usual culprit

  • A dirty throttle body is the most common cause of P1243 on Hondas, and cleaning it often resolves the code without any parts replacement.
  • The code can set intermittently from a momentary glitch in the APP sensor signal that does not leave a permanent fault, so always check freeze frame data before condemning parts.
  • After cleaning or replacing the throttle body, a Honda-specific idle relearn or PCM reset is mandatory; skipping it will cause the code to return immediately.
  • A weak battery or poor ground can cause voltage drops that mimic a TPS fault, so load-test the battery and inspect ground straps before replacing sensors.
  • P1243 can be stored alongside P2138 or P0122 when the APP and TPS signals disagree, pointing to a correlation fault rather than a single sensor failure.

Can I keep driving with P1243?

You can usually drive the vehicle to a repair shop, but expect reduced power and avoid heavy acceleration or highway merging until the fault is corrected. If the vehicle enters limp mode with severely limited throttle response, stop driving and arrange a tow to prevent a dangerous situation.

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 Honda vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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