P2135 on 2011-2016 Hyundai Elantra 1.8L: Throttle Position Sensor Causes and Fixes

What's Unique About the 2011-2016 Hyundai Elantra

For the 2011-2016 Elantra with the 1.8L Nu engine, the two throttle position sensors (TPS1 and TPS2) are integrated directly into the electronic throttle body assembly. They cannot be replaced individually. This design means that if one of the internal resistive tracks or sensors fails, the entire throttle body unit must be replaced. This is the most common point of failure for this code on this specific vehicle, a fact corroborated by numerous owner forums and repair databases.

Symptoms You May Notice

• Check Engine Light is on
• Vehicle enters 'Limp Mode' (Reduced Engine Power) with very slow acceleration.
• Hesitation or stumbling when pressing the gas pedal.
• Engine stalling, especially after coming to a stop.
• Unstable or rough idle, may be unusually high or low.
• Engine surging or revving unexpectedly without pedal input.
• Traction control light may also illuminate simultaneously.

Most Likely Causes

1. Faulty Electronic Throttle Body Assembly 🔴 High Probability The integrated throttle position sensors (TPS) are the primary failure point. The internal resistive tracks wear out over time, creating dead spots or erratic signals that the ECM flags as a correlation error.
   How to confirm: Using a scan tool with live data, graph the voltage of 'TPS1' and 'TPS2'. With the key on, engine off, slowly press the accelerator pedal. TPS1 voltage should rise smoothly from ~0.5-0.7V to ~4.5V, while TPS2 should do the inverse. Any spikes, dropouts, or flat spots in the graph confirm a failing sensor. Wiggling the connector during this test can help isolate a wiring issue.
   Typical fix: Replace the entire electronic throttle body assembly.
   Est. part cost: $150-$350
2. Dirty Throttle Body 🟡 Medium Probability Carbon and oil residue from the PCV system can build up around the throttle plate, causing it to stick or move slowly. This can cause the plate's actual position to lag behind the motor's command, leading to a temporary correlation fault between the sensors.
   How to confirm: Remove the air intake hose from the throttle body and visually inspect the throttle bore and plate for black carbon buildup.
   Typical fix: Clean the throttle body bore and plate thoroughly with a dedicated throttle body cleaner and a soft cloth or brush. Do NOT push the throttle plate open with your fingers; have an assistant press the gas pedal (with key on, engine off) or use a non-marring tool. 🎬 See this video for a safe throttle body cleaning walkthrough.
   Est. part cost: $5-$15
3. Wiring or Connector Issue ⚪ Low Probability The wiring harness connector at the throttle body is exposed to engine heat and vibration, which can lead to corrosion on pins or frayed wires near the connector.
   How to confirm: Visually inspect the throttle body connector for corrosion, bent pins, or damaged wires. With the scan tool graphing TPS voltages, gently wiggle the connector and wiring harness to see if the signal becomes erratic.
   Typical fix: Clean the connector terminals with a contact cleaner or repair the damaged section of the wiring harness. Applying dielectric grease during reassembly can prevent future corrosion.
   Est. part cost: $0-$50

Rare But Worth Checking

• Failing Powertrain Control Module (PCM): This is very uncommon. The PCM should only be considered after a new throttle body and verified wiring fail to resolve the code.
• Faulty Accelerator Pedal Position (APP) Sensor: While part of the same system, a failing APP sensor usually generates its own specific trouble codes (like P2138). It is an unlikely cause for P2135.

Diagnosis Steps

1. Scan for Codes: Confirm P2135 is the primary code. Note any other codes, like P0638, that may be present.
2. Inspect the Wiring: Turn the ignition off. Carefully inspect the electrical connector and wiring harness going to the throttle body. Look for any signs of damage, corrosion, or loose connections.
3. Clean the Throttle Body: Remove the intake boot. If significant carbon buildup is visible, clean it thoroughly. SAFETY WARNING: Do not force the throttle plate open with your fingers. Have an assistant press the accelerator pedal with the ignition ON (engine OFF) to open the plate for cleaning. This is a low-cost step that frequently resolves the issue.
4. Analyze Live Data: Connect a scan tool that can display live data. With the key on and engine off, monitor the voltage readings for TPS1 and TPS2. TPS1 should read approx. 0.5-0.7V and TPS2 should read approx. 4.5V at closed throttle. As you slowly press the gas pedal, the voltages should change smoothly and inversely. Any sudden jumps, drops, or freezing in the voltage indicates a sensor failure within the throttle body.
5. Confirm the Failure: If the wiring is good and cleaning did not help, and the live data shows a clear correlation error, the throttle body assembly has failed and requires replacement.
6. Replace the Throttle Body: If confirmed faulty, replace the entire throttle body assembly with a new or remanufactured unit. The OEM part number is 35100-2E000.
🎬 Watch: Step-by-step guide to testing and replacing the throttle body.
7. Perform Relearn Procedure: After replacement or cleaning, a throttle relearn is mandatory. A common procedure for Hyundai is: Turn the ignition to the 'ON' position (do not start engine) for 10-15 seconds. You may hear the throttle body motor whirring. Turn the ignition 'OFF' for 10-15 seconds. Repeat this cycle 3-5 times. Then, start the engine and let it idle for 5-10 minutes to allow the ECM to adapt. Alternatively, disconnecting the battery for 15-30 minutes can also force a reset.

Parts You'll Likely Need

• Electronic Throttle Body Assembly (OEM #35100-2E000) — This is the most common cause of P2135, as the internal throttle position sensors fail and are not serviceable separately. This part number is confirmed to fit the 2011-2016 Elantra 1.8L and several other Hyundai/Kia models.
  Trusted brands: Hyundai (OEM), Bosch, Standard Motor Products (SMP), Cardone (Remanufactured)
  OEM price range: $250-$350
  Aftermarket price range: $150-$250

Related Codes That Often Appear With This One

• P0638 - Throttle Actuator Control Range/Performance

Technical Service Bulletins (TSBs) & Recalls

• While no TSB directly addresses P2135 for this specific model, Hyundai has issued related software updates for similar engine platforms. For example, TSB 19-AT-010H provides a procedure for transferring oil pressure data to the ECU/TCU using the GDS Mobile tool to improve shift quality after a transmission or TCU replacement, showing a history of using software to manage component characteristics.
• Manufacturer service records for other Hyundai models, such as NHTSA ODI #11019236, indicate that owners have found TSBs related to the P2135, P2106, and P1295 code cluster, suggesting a widespread pattern of electronic throttle control issues across the brand's platforms.

Platform-Specific Known Issues

• Owner Experience: Intermittent Failure in Cold Weather: Multiple owners report that the P2135 code and limp mode symptoms are more likely to occur during a cold start, especially on cold days. The vehicle may operate normally after warming up and being restarted, only for the problem to return the next morning. This intermittent behavior points towards failing electronic components within the throttle body that are sensitive to temperature changes.
• Real-World Repair Story: Cleaning vs. Replacement: On Hyundai-Forums, a user with a 2013 Elantra experiencing P2135 and limp mode first attempted to resolve the issue by thoroughly cleaning the throttle body. While the car ran better initially, the code returned within a week. Replacing the entire throttle body assembly with an OEM part (35100-2E000) and performing the key-cycle relearn procedure permanently fixed the issue. This highlights that while cleaning is a valid first step, it is often a temporary solution if the sensors themselves are failing.

Mechanic-Grade Diagnostic Values

• Throttle Body Connector Pin 5 (TPS1 Signal) to Pin 4 (Sensor Ground) — expected: Approx. 0.5V - 0.7V at closed throttle, sweeping smoothly to ~4.5V at wide-open throttle.. Failure: Voltage that is erratic, jumps, or has flat spots during the sweep.
• Throttle Body Connector Pin 3 (TPS2 Signal) to Pin 4 (Sensor Ground) — expected: Approx. 4.5V at closed throttle, sweeping smoothly down to ~0.5V at wide-open throttle.. Failure: Voltage that does not move inversely to TPS1 or has spikes/dropouts.
• Throttle Body Connector Pin 6 (5V Reference) to Pin 4 (Sensor Ground) — expected: Stable 5.0V with key on, engine off.. Failure: Voltage that is low, high, or unstable indicates a PCM or wiring issue.
• Throttle Body Bolt Torque — expected: 7.8 to 11.8 Newton-meters (5.8 to 8.7 ft-lb). Failure: Improper torque can lead to vacuum leaks or damage to the throttle body.

Scan Tool Commands That Help

• Hyundai GDS (Global Diagnostic System): Active Test -> ETC Motor — This bidirectional command allows the technician to command the Electronic Throttle Control (ETC) motor to open and close, verifying the motor's function independently of the pedal. It's used to confirm if the throttle plate is physically sticking or if the motor itself has failed.
• Hyundai GDS: S/W Management -> Reset Adaptive Values — After replacing the throttle body or cleaning it, this function can be used to reset the ECM's learned values for throttle position, forcing it to recalibrate to the new or cleaned part. This is a more robust alternative to the key-cycle or battery disconnect methods.

Wiring & Ground Locations

• Throttle Body Connector (6-pin) — Connected directly to the electronic throttle body, located between the air intake hose and the engine's intake manifold.. This is the primary connection point for both throttle position sensors (TPS1, TPS2), the 5V reference, sensor ground, and the two wires for the throttle actuator motor. A bad connection, corrosion, or damaged wire at this connector is a common cause of P2135. The pinout is critical for testing: Pin 1 (Motor +), Pin 2 (Motor -), Pin 3 (TPS2 Signal), Pin 4 (Sensor Ground), Pin 5 (TPS1 Signal), Pin 6 (5V Reference).
• G101 (Main Engine Ground) — Typically a strap or cable connecting the engine block to the chassis, often near the transmission mount or on the fender apron.. A poor engine ground can create voltage offsets and electrical noise, causing sensor readings to become unstable. The ECM relies on a solid ground reference for all its sensors, including the TPS. An unstable ground can cause the TPS1 and TPS2 signals to appear uncorrelated to the ECM, triggering P2135. The OEM ground strap for the 2011-2015 1.8L Elantra is part number 91865-3X010.

Real Owner Repair Stories

• Reddit user KrellBH (2017 Hyundai Santa Fe (similar electronic throttle control system)) — Really rough shifts from 1st to 2nd gear, with a loud 'clunk' and lurching.
  ✅ What actually fixed it Performing a 5-cycle key ON/OFF throttle relearn procedure completely smoothed out the shifts. This confirms the effectiveness of the manual relearn process for resolving drivability issues related to throttle calibration.
• NHTSA ODI #10846204 (Hyundai Sonata) — An owner reported that after the vehicle lost pedal response, they shut off the engine and restarted it, which temporarily restored acceleration. The diagnostic scan revealed codes P2135, P0221, P2106, P0121, and P2110.
• NHTSA ODI #11061416 (Hyundai Veracruz) — A driver experienced a second occurrence of the check engine light and P2135 code while driving on a highway, which caused the car to enter "limp home mode."

OEM Part Supersession History

• 35100-2E000 → N/A — This part number remains the primary OEM replacement for the 2011-2016 Elantra 1.8L.
  Heads up: While 35100-2E000 is the correct part, be aware that it is also used on some 2.0L applications in other Hyundai/Kia models like the Tucson and Forte. Always verify fitment by VIN, but for the 2011-2016 Elantra 1.8L, this is the correct assembly.

Model Year Variations Within This Range

• 2014-2016: A mid-cycle refresh for the 2014 model year introduced revised styling and an optional 2.0L GDI engine (173 hp) on higher trims. While the base 1.8L engine remained the volume seller and uses the same throttle body (35100-2E000), a technician should always confirm the engine size before ordering parts, as the 2.0L engine became more common in these later years.
• 2011-2013: These pre-facelift models were more likely to come standard with the 1.8L Nu engine (148 hp, later revised to 145 hp). The P2135 diagnosis is identical, but there is less chance of encountering the 2.0L engine seen in later years.

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 reputable salvage yard can be a smart choice if it comes from a low-mileage, rear-ended donor vehicle. Since the failure is electronic wear, a newer, lower-mileage part offers significant cost savings ($50-$150) with a good chance of having substantial remaining life.

Donor-vehicle mileage cap: roughly under 60000 miles for the part to have meaningful remaining life.

What to inspect on the donor part:

• Verify the OEM part number (35100-2E000) is stamped on the housing.
• Inspect the electrical connector pins for any signs of corrosion, moisture, or damage.
• Check the throttle plate for excessive carbon buildup; a relatively clean bore suggests better vehicle maintenance.
• Ask for the donor vehicle's VIN and mileage to verify its history.
• Ensure there is a return policy (e.g., 30-90 days) in case the part is also faulty.

Aftermarket brands forum-validated for this vehicle:

• Bosch
• Standard Motor Products (SMP)

Brands owners have reported issues with on this vehicle:

• Unbranded, no-name parts from online marketplaces should be avoided, as their internal electronics may not meet OEM specifications for sensor accuracy and longevity, leading to a repeat failure.

Documented NHTSA Reports

Real Owner Stories

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

Related OBD-II Codes

• P0638 — Throttle Actuator Control Range/Performance. This code is often present with P2135 as it relates to the physical performance of the throttle plate motor, which can be compromised by the same issues (e.g., carbon buildup) that cause sensor correlation faults.
• P0122 — Throttle Position Sensor 'A' Circuit Low. Can be triggered alongside P2135 if the primary TPS sensor fails by shorting or if a wiring issue causes a signal loss. It indicates a specific electrical fault in one of the two sensors that P2135 monitors for correlation.
• P0223 — Throttle Position Sensor 'B' Circuit High. Similar to P0122, this code points to a specific failure in the second TPS sensor (e.g., short to voltage). Its presence reinforces the diagnosis of a failed electronic throttle body assembly, the primary cause of P2135.
• P2106 — Throttle Actuator Control System - Forced Limited Power. This is an informational code indicating the Engine Control Module has put the vehicle into 'Limp Mode' as a direct result of detecting the P2135 fault. It describes the effect, not the cause.
• P2110 — Throttle Actuator Control System - Forced Limited RPM. Like P2106, this code confirms the ECU has taken protective action by limiting engine RPM because of the critical sensor correlation error reported by P2135.

Frequently Asked Questions