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DTC codes / Honda codes / P1122

P1122 · HondaThrottle Position Higher Than Expected

P1122 on a Honda means the powertrain control module (PCM) has detected a throttle position sensor (TPS) signal voltage that is higher than the programmed limit for the current operating conditions. In plain English, the computer sees the throttle as being open wider than it should be, which can upset idle quality, fuel delivery, and automatic transmission shift logic.

SystemPowertrain
Code typeHonda specific
SeverityMedium
Fix difficultyIntermediate
AreaFuel and air metering

Symptoms you may notice

  • Illuminated check engine light, often with no other noticeable symptoms
  • Unstable or surging idle, especially when the engine is cold or under electrical load
  • Automatic transmission shifting harshly or at the wrong points because the PCM misjudges engine load
  • Reduced engine power or a limp-home mode on some models
  • Poor fuel economy from the PCM enriching the mixture based on a falsely high throttle reading
  • Occasional stalling when coming to a stop if the idle control strategy is confused

Common causes, most likely first

  1. Throttle position sensor (TPS) internally worn or failing, producing a skewed high voltage
  2. Dirty or sticking throttle body and throttle plate preventing the sensor from returning to its expected closed position
  3. Damaged or corroded TPS connector, or chafed wiring shorting the signal circuit toward reference voltage
  4. Improperly adjusted or loose TPS mounting on cable-driven throttle bodies
  5. PCM software calibration issue or internal PCM fault on certain Honda models
  6. Aftermarket throttle body or TPS installed with incorrect resistance characteristics
  7. Contaminated throttle body from oil carryover or carbon buildup causing the plate to rest slightly open

How to diagnose and fix it

  1. Scan all modules and record freeze-frame data for P1122, then clear the code and verify whether it returns immediately or only under specific conditions
  2. Visually inspect the throttle body, throttle plate, and TPS connector for carbon buildup, corrosion, or loose pins
  3. Back-probe the TPS signal wire and compare voltage at closed throttle and wide-open throttle against Honda specifications
  4. Clean the throttle body with approved cleaner and perform a throttle body adaptation or idle relearn procedure
  5. Check TPS mounting adjustment and replace the TPS if its voltage curve is non-linear or out of range
  6. Perform a wiggle test on the TPS harness while watching live data to catch intermittent signal spikes
  7. If all inputs are correct, check for PCM calibration updates or internal PCM faults before replacement

Why a clean throttle body often fixes P1122

  • A throttle plate that is only slightly carboned up can hold the TPS voltage just above the expected closed-throttle value, setting P1122 without any driveability complaint.
  • Many technicians replace the TPS first, but Honda cable-driven throttle bodies often need the sensor adjusted after cleaning, and a new sensor installed without adjustment will set the code again.
  • P1122 can be set by a poor ground at the throttle body or engine block, which raises the signal voltage reference and mimics a failing sensor.
  • On some Hondas, a weak battery or a recent battery replacement can cause a false P1122 until the idle learn procedure is completed.
  • The code does not always mean the TPS is bad; a sticking throttle cable or cruise control actuator holding the plate open will produce the same high-voltage signal.

Can I keep driving with P1122?

You can usually drive the vehicle short distances to a repair shop, but avoid aggressive acceleration and towing because the PCM may be using an incorrect throttle reading for fuel and shift control. If the engine idles very high or surges unpredictably, stop driving and have it towed.

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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