P2135 on 2011-2015 Honda Civic: Throttle Position Sensor Failure Causes and Fixes

What's Unique About the 2011-2015 Honda Civic

For the 8th and 9th generation Honda Civic, the most common point of failure for a P2135 code is the Throttle Position Sensor (TPS). Unlike older vehicles where the TPS was a separate, inexpensive part, Honda integrated the sensor into the electronic throttle body assembly on these models. This means a simple sensor failure requires the replacement of the entire, more costly, throttle body unit. While the Accelerator Pedal Position (APP) sensor can also cause this code, it is a much less frequent issue on this platform, and is more commonly associated with code P2138.

Generation note: This range covers the final year of the 8th generation (2011) and the 9th generation (2012-2015). The cause and repair, typically a throttle body replacement, are consistent for the common 1.8L (R18) engine across these years. The issue is also seen on the 8th generation Civics.

Symptoms You May Notice

• Check Engine Light is on
• Flashing 'D' (Drive) indicator light on the dashboard
• Vehicle enters 'limp mode' (reduced engine power)
• Poor, delayed, or hesitant acceleration
• Unstable or surging idle
• Engine may stall when coming to a stop
• No response when pressing the gas pedal

Most Likely Causes

1. Failed Throttle Position Sensor (Integrated into Throttle Body) 🔴 High Probability → Shop Fuel Injection Throttle Body The electronic sensors integrated into the throttle body assembly are a common failure point as the vehicle ages due to heat and vibration. Honda does not sell the sensor separately for this model.
   How to confirm: Use a scan tool with live data to graph the voltage of TPS Sensor 1 (TP1) and TPS Sensor 2 (TP2). As you slowly press the gas pedal with the key on and engine off, the two voltage readings should move smoothly and in tandem. One should rise (e.g., ~0.5V to ~4.5V) while the other falls. Any signal that jumps, drops out, freezes, or is erratic indicates the sensor is bad. The PCM expects the sum of the two sensor voltages to be a constant value (around 5V); if this sum deviates, the code is set.
   Typical fix: Replace the entire throttle body assembly with a new gasket. After replacement, a throttle body idle relearn procedure must be performed for the engine to idle correctly.
   Est. part cost: $200-$450
2. Damaged Wiring or Poor Connection at Throttle Body 🟡 Medium Probability → Shop Fuel Injection Throttle Body The wiring harness connector at the throttle body is exposed to engine vibration and heat, which can cause wires to fray or pins to lose connection over time.
   How to confirm: Visually inspect the wiring harness and connector going to the throttle body. Wiggle the connector with the engine running to see if it causes a change in idle or triggers the code. Check for corrosion, backed-out pins, or broken wires. A multimeter can be used to check for continuity between the PCM connector and the throttle body connector.
   Typical fix: Repair the damaged section of wiring or replace the connector pigtail. In a documented case on a similar Honda model, a Toyota pigtail (Part No. 90980-11858) for a Denso throttle body was used as a compatible replacement. Aftermarket pigtail connectors are also available.
   Est. part cost: $15-$50
3. Failed Accelerator Pedal Position (APP) Sensor ⚪ Low Probability → Shop Accelerator Pedal Assembly
   How to confirm: Use a scan tool to monitor the live data for APP Sensor 1 and APP Sensor 2. As you press the gas pedal, the voltages should change smoothly without glitches. A user on a Honda Fit forum initially suspected the APP sensor after wiggling its connector seemed to temporarily resolve the issue, but the P2135 code returned, pointing back to the throttle body.
   Typical fix: Replace the accelerator pedal assembly, which contains the integrated sensors.
   Est. part cost: $150-$250

Rare But Worth Checking

• Faulty Powertrain Control Module (PCM): → Shop Engine Control Module (ECM) This is extremely rare and can be caused by internal circuit failure. The PCM should only be considered after all other possibilities, including sensors and wiring, have been exhaustively tested and ruled out.
• Dirty Throttle Body: → Shop Fuel Injection Throttle Body While less likely to cause a correlation code than outright failure, heavy carbon buildup can cause the throttle plate to stick, which may lead to erratic sensor readings. Cleaning the throttle body is a good preliminary step.

Diagnosis Steps

1. Read the code with an OBD-II scanner and confirm P2135 is present. Note any other codes.
2. Check for any Technical Service Bulletins (TSBs) for your vehicle's year and model related to P2135. While no specific Honda TSB was found, GM has issued TSBs for P2135 on their vehicles related to TPS and wiring issues.
3. With the ignition on and engine off, use a scan tool to view live data for the two Throttle Position Sensors (TPS1, TPS2) and the two Accelerator Pedal Position Sensors (APP1, APP2).
4. Slowly press and release the gas pedal, watching the APP sensor voltages. They should move smoothly without any glitches or dropouts.
5. While observing the TPS voltages, slowly open and close the throttle plate by hand (if accessible) or have a helper press the pedal. The two TPS voltages should mirror each other smoothly (one typically rises from ~0.5V to ~4.5V, while the other falls). Any jumping, freezing, or dropouts in the voltage indicates a faulty TPS.
🎬 See this guide on how to test your throttle position sensor.
6. If the sensor data appears normal, thoroughly inspect the wiring harness and connector at the throttle body for any signs of damage, corrosion, or loose pins. Wiggle the harness to see if the fault can be induced.
7. If the TPS data is erratic, the throttle body assembly is the most likely cause. If the APP data is erratic, the accelerator pedal assembly is the cause. The TPS is the more common failure for this code on this vehicle.
8. If replacing the throttle body, perform the Idle Relearn Procedure after installation.

Parts You'll Likely Need

• Throttle Body Assembly (OEM #16400-R1A-A01) — This is the most common fix because the failure-prone Throttle Position Sensor (TPS) is integrated into this assembly for the 2011-2015 Civic.
  Trusted brands: Honda (OEM), Hitachi (OEM supplier), WVE/NTK, Cardone (Remanufactured)
  OEM price range: $350-$650
  Aftermarket price range: $200-$300
• Throttle Body Gasket (OEM #17107-RNA-A01) — A new gasket is required when replacing the throttle body to ensure there are no vacuum leaks.
  Trusted brands: Honda (OEM), Fel-Pro
  OEM price range: $15-$25
  Aftermarket price range: $5-$10

Technical Service Bulletins (TSBs) & Recalls

• No specific Honda TSBs for P2135 on this platform were found during research. However, GM has issued TSBs like 12-06-04-003A for P2135 on their vehicles, which points to a pattern of TPS and wiring issues being the root cause across manufacturers.

Platform-Specific Known Issues

• Idle Relearn Procedure is Critical: After replacing or cleaning the throttle body, or even disconnecting the battery, the PCM's adaptive memory for idle control is lost. A specific idle relearn procedure must be performed. Failure to do so will result in an unstable, high, or hunting idle. The procedure generally involves warming the engine fully, then letting it idle with no electrical load for 5-10 minutes until the radiator fan cycles.
🎬 Watch: How to perform the idle relearn procedure without a scanner.

Mechanic-Grade Diagnostic Values

• Throttle Position Sensor (TPS) A & B Voltage Sum — expected: Constant 5V. Failure: If the sum of the two sensor voltages deviates from 5V for more than 200 milliseconds, the PCM detects a malfunction.
• Throttle Position (TP) Sensor Voltage (Key On, Engine Off) — expected: ~0.5V - 0.7V at closed throttle, ~4.0V - 4.5V at wide-open throttle.. Failure: Readings that are erratic, jump, or do not change smoothly indicate a faulty sensor.
• Accelerator Pedal Position (APP) Sensor Voltage (Key On, Engine Off) — expected: ~0.5V - 0.9V with pedal released, ~3.5V - 4.5V at full throttle.. Failure: Voltage that doesn't change smoothly or has dropouts indicates a faulty APP sensor.

Scan Tool Commands That Help

• Honda Diagnostic System (HDS): ETCS TEST (Electronic Throttle Control System) — This function is used to test the throttle control system and verify if the P2135 fault is current or intermittent after clearing the code.
• Honda Diagnostic System (HDS): TP POSITION CHECK — Allows for viewing the throttle position learning value and resetting it. This is often required after cleaning or replacing the throttle body to resolve high or erratic idle issues.
• Honda Diagnostic System (HDS): Reset ECM — Used to clear the PCM's learned values after a repair, such as replacing the throttle body. This must be followed by an idle relearn procedure.

Wiring & Ground Locations

• G101 — Typically located on the engine block or transmission housing, serving as a primary ground for the PGM-FI system.. A poor connection at G101 can cause erratic behavior in various engine sensors, including the throttle body sensors, potentially leading to a P2135 code. The PGM-FI subrelay circuit and ETCS throttle control system relay ground through here.
• PCM Connector C (44-pin) — At the Powertrain Control Module (PCM).. This connector contains the signal wires for the throttle position sensors. Specifically, pin C12 provides the VCC3 (5V reference) to both TPS A and B. Checking for continuity and shorts between pins C20 (TPSA) and C21 (TPSB) is a key diagnostic step.
• Throttle Body 6-Pin Connector — Directly on the electronic throttle body assembly.. This is the primary connection point for the throttle position sensors and throttle actuator motor. It is a common point of failure due to heat and vibration causing loose pins or corrosion. A 'tug test' on the wires entering this connector can reveal a poor internal crimp.

Real Owner Repair Stories

• Chevy HHR Network Forum (2010 Chevrolet HHR 2.2L (Similar Denso electronic throttle system)) — Car running rough, multiple dash lights (low power, traction control), shaking, then clearing up with only a check engine light for P2135.
  ❌ Tried (didn't work) Considering throttle body replacement.
  ✅ What actually fixed it The owner performed a 'tug test' on the wires at the throttle body connector and found a loose gray wire. Replacing the single pin within the connector resolved the issue completely without replacing the throttle body.
• NHTSA ODI #10537865 (Honda Accord — Cross-model reference) — An owner reported that a technician found DTC code P2135 for TP sensor A/B incorrect voltage correlation. The technician initially attempted to recalibrate the TP sensor to resolve the issue.
• NHTSA ODI #11479189 (Honda Pilot — Cross-model reference) — An owner experienced the P2135 code five times, which caused the dashboard warning lights to flash numerous warnings and forced the vehicle into an immediate reduced-power state.

Diagnostic Flowchart

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: A used OEM throttle body from a low-mileage donor vehicle can be a reliable and cost-effective alternative to a new OEM unit, and is often preferable to a new, non-OEM aftermarket part with questionable electronics.

Donor-vehicle mileage cap: roughly under 75000 miles for the part to have meaningful remaining life.

What to inspect on the donor part:

• Verify the part number from the donor vehicle matches your requirement exactly; different engines use non-interchangeable parts.
• Inspect the electrical connector pins to ensure they are straight, clean, and free of corrosion.
• Gently move the throttle plate by hand; it should move smoothly without any sticking or binding.
• Avoid units with excessive carbon buildup, as this may indicate high mileage or poor engine maintenance on the donor car.

OEM-only on this vehicle (don't cheap out):

• Throttle Position Sensor (if attempting to replace separately, which is not standard procedure for this vehicle)

Aftermarket brands forum-validated for this vehicle:

• Hitachi (often the original OEM supplier)
• Standard Motor Products (SMP)

Brands owners have reported issues with on this vehicle:

• Unbranded, no-name throttle bodies from online marketplaces are frequently cited in forums as failing quickly or being defective out of the box.

Real Owner Stories

Aggregated from forums and TSBs cited above. Mileages and costs reflect what owners reported in those sources.

Related OBD-II Codes

• P0121 — Throttle Position Sensor 'A' Circuit Performance/Range. This code may accompany P2135 as it indicates a general fault with one of the two sensors the PCM is comparing.
• P0122 — Throttle Position Sensor 'A' Circuit Low. This code can be a root cause for P2135, as a sensor stuck in a low voltage state will fail the correlation check against the second sensor.
• P0123 — Throttle Position Sensor 'A' Circuit High. Similar to P0122, this indicates a sensor stuck reading high, which would cause the voltage correlation to fail and trigger P2135.
• P2138 — Throttle/Pedal Position Sensor 'D'/'E' Voltage Correlation. This is the equivalent correlation code for the Accelerator Pedal Position (APP) sensor. It may appear if the APP sensor, a less common cause, is the source of the fault.
• P2122 — Accelerator Pedal Position Sensor 'D' Circuit Low. If the APP sensor is the cause of the driveability issue, this specific circuit code may appear alongside or instead of P2135.
• P2127 — Accelerator Pedal Position Sensor 'E' Circuit Low. This points to a fault in the second APP sensor, which would also cause a correlation error with the first APP sensor, relating it to the same diagnostic family as P2135.

Frequently Asked Questions