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DTC/P0122·Honda

P0122 on Honda: Causes, Symptoms and Fix Cost

Quick Answer
Moderate SeverityNot safe to driveHonda

P0122 on a Honda means the ECU is seeing an abnormally low voltage on throttle position sensor circuit A, typically under 0.2V when it expects 0.5V to 4.5V. Most cars drop into limp mode with capped throttle.

Connect any standard Bluetooth OBD2 adapter to your Honda and Skanyx tells you what P0122 means on that engine, whether it is safe to keep driving, and what the fix should cost. Free on iPhone and Android.

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What does P0122 mean on a Honda?

The Quick Answer above is the generic definition. What follows is what is documented for the Honda models that log P0122, checked against manufacturer data and owner reports.

Honda Civic

2006-2015 (R18A 1.8L, 8th and 9th gen)

Uncommon on the Civic, but when it appears the throttle body assembly (Honda part 16400-RNA-A01) is the usual culprit. Honda requires the idle learn procedure (ignition on 2 minutes, then 5 minutes at operating temp) after any throttle work.

What causes P0122 on a Honda?

Beyond the generic causes listed on the main P0122 page, these are the documented Honda-specific patterns:

Honda CivicCarbon buildup preventing the throttle plate from returning to true closed position
Honda CivicCracked solder joint on the TPS board inside the throttle body

How to diagnose P0122 on a Honda with OBD2

Follow these steps to pinpoint the root cause of P0122:

  1. Read all stored codes and note companion codes such as P0113, P0222, or P2135
  2. Watch live data for TPS1 voltage with key on, engine off. Below 0.2V confirms the low input
  3. Wiggle the throttle body connector and harness while watching live data to catch intermittent faults
  4. Backprobe the TPS signal, 5V reference, and ground pins with a multimeter. Reference should read 4.9 to 5.1V
  5. If reference and ground are good but signal stays near 0V, replace the TPS or throttle body
  6. If the 5V reference is missing, check the wiring back to the ECU for a short to ground
  7. After repair, clear codes and run the throttle body relearn per the manufacturer procedure
  8. Road test and confirm TPS voltage sweeps smoothly from ~0.5V at closed throttle to ~4.5V at WOT

How much does P0122 cost to fix on a Honda? (EUR)

Estimated repair costs for P0122 in EUR, compiled across makes. Honda parts and labour usually land towards the lower end of each range.

Repair Parts Cost Labor Cost Total Estimate DIY Difficulty
Clean and reseat throttle body connector €0–€10 €0–€40 €0–€50 Easy
Replace standalone throttle position sensor €30–€120 €40–€90 €70–€210 Easy
Replace electronic throttle body assembly €180–€550 €80–€180 €260–€730 Moderate
Repair damaged wiring or connector pins €10–€40 €60–€180 €70–€220 Moderate
ECU diagnosis and replacement (worst case) €400–€1200 €100–€250 €500–€1450 Professional

Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.

These codes commonly cluster with P0122 on Honda vehicles:

P0121HondaP0123HondaP0124P2135P0222

Looking for the full P0122 reference (all makes, full diagnosis flow, complete repair cost matrix)?

See the main P0122 guide
Skanyx · Honda

Diagnose P0122 on your Honda

Your car logged P0122. Skanyx reads it on any standard Bluetooth OBD2 adapter, tells you whether it is safe to keep driving, and breaks down the likely repair so you know the number before a shop quotes you. Free on iPhone and Android, and you do not need to be a mechanic to read it.

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