P2135 on 2017-2023 Honda Accord: Throttle Position Sensor Failure, Causes, and Fixes

What's Unique About the 2017-2023 Honda Accord

For modern Hondas like the 2017-2023 Accord, the dual throttle position sensors (TPS) are built directly into the electronic throttle body assembly. Honda does not sell the sensors separately from the throttle body. This means that a failure of the internal sensor tracks, a common wear-and-tear issue, requires the replacement of the entire throttle body unit rather than just a small sensor. This design choice makes the repair more expensive but also more straightforward as it eliminates the possibility of misdiagnosing a faulty sensor versus a faulty throttle motor.

Generation note: The 2017-2023 year range covers three generations of the Honda Accord: the end of the 9th Gen (2017), the full 10th Gen (2018-2022), and the start of the 11th Gen (2023). The causes and repair procedures for P2135 are consistent across these modern 'drive-by-wire' generations, particularly affecting the common 1.5T and 2.0T engines.

Symptoms You May Notice

• Sudden and significant loss of engine power (Limp Mode)
• Check Engine Light is on
• Flashing 'D' (Drive) indicator light on the dashboard
• Vehicle hesitates or won't accelerate when pressing the gas pedal
• Erratic or rough idle, sometimes idling high (e.g., 1500-2000 RPM)
• Multiple warning lights on the dashboard simultaneously, such as Vehicle Stability Assist (VSA), Collision Mitigation Braking System (CMBS), and Tire Pressure Monitoring System (TPMS) errors, as the throttle control data is critical for these systems.

Most Likely Causes

1. Faulty Throttle Body Assembly 🔴 High Probability → Shop Fuel Injection Throttle Body The throttle position sensors (TPS) are integrated into the assembly and are a common failure point due to wear on the internal electronic tracks. The OEM does not service the sensor separately. This is a known issue across multiple Honda platforms using the same engine families.
   How to confirm: Use a scan tool with live data to graph the voltage of TPS Sensor 1 and Sensor 2. As you slowly press the accelerator pedal, the two voltage readings should move smoothly and in opposition (one rising, one falling). A jump, drop, or flat line from one sensor, or a signal that doesn't mirror the other, indicates failure. The faulty signal often appears as a sudden 'glitch' or 'drop-out' in the voltage graph.
   Typical fix: Replace the entire throttle body assembly. A mandatory throttle body 'relearn' procedure must be performed after installation.
   Est. part cost: $200-$500
2. Faulty Accelerator Pedal Position (APP) Sensor 🟡 Medium Probability → Shop Accelerator Pedal Assembly The APP sensor, located on the gas pedal assembly, also uses dual sensors for redundancy. Like the TPS, it can wear out over time, causing correlation faults. However, P2135 is more frequently associated with the throttle body itself, while code P2138 points more directly to the APP sensor.
   How to confirm: Using a scan tool, monitor the live data for APP Sensor 1 and APP Sensor 2. The voltage should increase smoothly as the pedal is depressed. Any erratic readings or dropouts point to a faulty sensor. This test should be performed after confirming the TPS signals are clean to avoid misdiagnosis.
   Typical fix: Replace the accelerator pedal assembly. This is a simple bolt-on part with an electrical connector.
   Est. part cost: $150-$250
3. Wiring or Connector Issue ⚪ Low Probability Engine vibration and heat can, over time, cause damage to the wiring harness or corrosion in the connector at the throttle body. The wiring harness to the throttle body can be tight from the factory, putting stress on the wires and pins.
   How to confirm: Visually inspect the wiring harness and connector pins for the throttle body and accelerator pedal sensor. Check for corrosion, bent pins, or loose connections. With the engine running, gently wiggle the connector and harness to see if it induces the fault. A user on a Honda Fit forum traced a P2135 to a frayed wire right at the throttle body connector due to a tight harness, which was repaired by soldering in a small extension.
   Typical fix: Repair the damaged section of wiring or clean/replace the connector. In some cases, a new connector pigtail may need to be spliced in.
   Est. part cost: $10-$50

Rare But Worth Checking

• Faulty Powertrain Control Module (PCM): → Shop Engine Control Module (ECM) This is very rare. The PCM should only be considered after the throttle body, pedal sensor, and all related wiring have been thoroughly tested and confirmed to be good. A faulty PCM driver for the sensor circuits could theoretically cause this code.

Diagnosis Steps

1. Read the codes with an OBD-II scanner. Confirm P2135 is present and note any other codes like P2138 or P2101.
2. Use a scan tool to view live data. Graph the voltage signals from 'TPS A' and 'TPS B' (or TPS1/TPS2).
3. With the key on but the engine off, slowly press and release the gas pedal. The two sensor voltages should change smoothly and mirror each other (one may be inverse of the other, but the pattern should be identical). If one or both signals are erratic, jumpy, or flat, the throttle body assembly is almost certainly faulty.
4. If the TPS signals look good, repeat the live data test for the 'APP Sensor A' and 'APP Sensor B' from the accelerator pedal. Check for smooth, corresponding voltage changes.
5. If sensor data appears normal, perform a wiggle test. With the live data graph running, gently wiggle the wiring harness and electrical connector at the throttle body. If this causes the voltage to jump or drop out, you have a wiring issue.
6. If the wiring is intact and the sensors test good, the issue could be an intermittent failure. Given the high probability of throttle body failure on this platform, if the problem is easily repeatable, replacing the throttle body is the most probable solution.
7. After any replacement, perform the throttle body relearn procedure. For many Hondas, this can be done without a scan tool.
8. a. Ensure all electrical accessories are off.
9. b. Turn the ignition to ON (II) for 2 seconds.
10. c. Start the engine and hold the RPM at 3,000 until the radiator fan cycles on, or the engine reaches operating temperature (approx. 194°F).
11. d. Let the engine idle for at least 5 minutes. The idle relearn is complete.
🎬 Watch: Easy Honda idle relearn procedure without special tools

Parts You'll Likely Need

• Throttle Body Assembly (OEM #16400-RPY-G01 (for 2.0T engine), 16400-6A0-A02 (for 1.5T engine)) — This is the most common cause of P2135, as the internal throttle position sensors fail and are not sold separately by Honda.
  Trusted brands: Honda (OEM), Bosch (e.g., 0280750570, though cross-reference is needed)
  OEM price range: $350-$500
  Aftermarket price range: $200-$350
• Accelerator Pedal Sensor Assembly — This is the second most likely cause if the throttle body tests good. The entire pedal assembly is replaced as a unit.
  Trusted brands: Honda (OEM), Hella, Intermotor
  OEM price range: $200-$300
  Aftermarket price range: $150-$220

Related Codes That Often Appear With This One

• P2138 — This code specifically points to a voltage correlation issue with the Accelerator Pedal Position (APP) sensor. If you see both, it increases the likelihood the issue is with the pedal assembly or its circuit.
• P0120-P0124 — These are general circuit fault codes for the Throttle Position Sensor 'A' (e.g., P0123 for 'Circuit High'). They can appear alongside P2135 if there is a specific circuit malfunction (like a short or open) in addition to the correlation error.
• P2101 — This code stands for 'Throttle Actuator Control Motor Circuit Range/Performance'. It indicates a problem with the motor that physically opens and closes the throttle plate. Seeing this with P2135 strongly points to a comprehensive failure within the throttle body assembly.

Technical Service Bulletins (TSBs) & Recalls

• TSB 23-010 (Acura): While for Acura models (TLX/RDX) with the related 2.0T engine, this TSB addresses software updates for drivability issues and codes like P0172 (Fuel System Too Rich) in certain

Platform-Specific Known Issues

• On the 1.5T and 2.0T engines, the failure is so common that many owners on forums consider the throttle body a wear item, with failures sometimes occurring before 100,000 miles.

Documented NHTSA Reports

• NHTSA ODI #10537865 describes a case where a technician found DTC code P2135 indicating TP Sensor A/B incorrect voltage correlation. The technician initially attempted to recalibrate the TP sensor, but the incident recurred.
• NHTSA ODI #11479189, while filed for a different Honda model (Pilot), illustrates the severity of the issue, noting that the P2135 code caused the dashboard to flash numerous warnings and the vehicle to enter an immediate limp mode.

Mechanic-Grade Diagnostic Values

• Throttle Position Sensor (TPS) Voltage at Idle — expected: ~0.5 V. Failure: Voltage is significantly different from 0.5V with the throttle plate closed.
• Throttle Position Sensor (TPS) Voltage at Wide-Open Throttle (WOT) — expected: ~4.5 V. Failure: Voltage does not reach approximately 4.5V when the throttle is fully open.
• Resistance between TPS signal wires (THL1 and THL2) at the PCM connector — expected: 1 MΩ (megaohm) or greater. Failure: Resistance is lower than 1 MΩ, indicating a short circuit between the two sensor signal wires.

Scan Tool Commands That Help

• Honda Diagnostic System (HDS) or compatible (e.g., Foxwell NT510): TP POSITION CHECK — This function is used to clear the throttle position (TP) learned value in the PCM. It is a required step after cleaning or replacing the throttle body to reset the stored values before performing the idle relearn procedure.
• Honda Diagnostic System (HDS): ETCS TEST (Electronic Throttle Control System Test) — This is an initial diagnostic step to check for pending or confirmed DTCs and verify if the P2135 fault is currently active after clearing codes.

Wiring & Ground Locations

• Throttle Body 6-Pin Connector — On the electronic throttle body assembly where the engine harness connects.. This is the primary connection point for the two throttle position sensors (TPSA/TPSB), their power (VCC), ground (SG), and the throttle actuator motor. A loose connection, corrosion, or damaged wire at this connector is a common cause of P2135. The specific pins are: Pin 1 (TPS1), Pin 2 (VCC - 5V Reference), Pin 3 (TPS2), Pin 4 (SG - Sensor Ground), Pin 5 (Motor -), Pin 6 (Motor +).
• G101 — At the top middle of the engine.. This is a primary engine ground point. A loose or corroded G101 can cause a variety of sensor and module issues, including erratic voltage readings that could potentially trigger a correlation code like P2135.
• PCM Connector E (80-Pin) — One of the main connectors at the Powertrain Control Module (PCM).. Diagnostic procedures require disconnecting this connector to perform continuity and short-circuit tests on the wires running between the PCM and the throttle body, helping to isolate a wiring fault from a component failure.

Real Owner Repair Stories

• Unofficial Honda FIT Forums (2012 Honda Fit M/T) — Engine shudders, CEL and traction control light come on, car enters limp mode. Code P2135.
  ❌ Tried (didn't work) Initially suspected a bad throttle body.
  ✅ What actually fixed it The owner noticed the throttle position sensor data was twitchy on a scan tool. Unplugging the accelerator pedal position sensor (APPS) connector made the twitching stop. After plugging the APPS connector back in securely, the problem was resolved, indicating a loose connection at the pedal was the root cause.

OEM Part Supersession History

• 16400-5A2-A01 → 16400-5A2-A02 — This is a common supersession for the throttle body used on 2.4L Accords (2013-2017) and CR-Vs. Part updates often address reliability issues or manufacturing improvements.

Diagnostic Flowchart

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: For this specific failure (P2135), buying a used throttle body is a significant gamble and generally not recommended. The internal electronic sensors are a known high-failure item. A used part from a donor vehicle may have significant wear and could fail soon after installation, repeating the original problem.

Donor-vehicle mileage cap: roughly under 40000 miles for the part to have meaningful remaining life.

What to inspect on the donor part:

• Verify the part number on the used unit matches the required OEM part number for your vehicle's engine (1.5T vs 2.0T).
• Inspect the electrical connector pins for any signs of corrosion, bending, or damage.
• Ask for the mileage of the donor vehicle; lower mileage is always preferable, but provides no guarantee of remaining life.
• Check the throttle plate for excessive carbon buildup, which might indicate a high-mileage or poorly maintained engine.

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

• Throttle Body Assembly

Aftermarket brands forum-validated for this vehicle:

• Bosch (often the original equipment manufacturer)

Brands owners have reported issues with on this vehicle:

• Unbranded, low-cost units from online marketplaces are frequently reported on forums to fail prematurely or be dead-on-arrival.

Real Owner Stories

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

Related OBD-II Codes

• P2138 — Accelerator Pedal Position (APP) Sensor Correlation. This code points more directly to a fault with the gas pedal sensor assembly. It is often investigated alongside P2135 because the ECU compares signals from both the APP and TPS sensors.
• P2101 — Throttle Actuator Control Motor Circuit Range/Performance. This code frequently accompanies P2135 because it indicates a problem with the electric motor that moves the throttle plate, which is housed in the same throttle body assembly as the failing position sensors.
• P0172 — System Too Rich (Bank 1). Mentioned in an Acura TSB for the related 2.0T engine. An erratic or incorrect throttle position signal from a failing sensor can cause the ECU to miscalculate the required fuel trim, leading to a rich condition.
• P2176 — Throttle Actuator Control System - Idle Position Not Learned. This code can appear with P2135 or after a repair if the mandatory throttle body relearn procedure is not performed correctly, preventing the ECU from establishing the proper idle position.

Frequently Asked Questions