P0113 on 2007-2012 Lexus ES 350: Intake Air Temp Circuit High Causes and Fixes

What's Unique About the 2007-2012 Lexus ES

For the 2GR-FE V6 engine in this Lexus ES 350, the Intake Air Temperature (IAT) sensor is not a separate, standalone part. It is integrated directly into the Mass Air Flow (MAF) sensor housing located on the engine's air intake tube. This means that if the IAT sensor component fails and triggers a P0113, you must replace the entire MAF sensor assembly. When this fault occurs, the ECM activates a fail-safe mode, assuming a default intake air temperature of 68°F (20°C) to keep the engine running. This can lead to noticeable performance issues, especially during cold starts or extreme weather conditions.

Symptoms You May Notice

• Check Engine Light is on
• Check VSC light may also illuminate
• Difficulty starting the engine, especially when cold
• Engine cranks but fails to start
• Reduced fuel economy
• Rough or unstable idle
• Engine hesitation or bucking during acceleration
• Black, fuel-fouled spark plugs

Most Likely Causes

1. Failed Mass Air Flow (MAF) / IAT Sensor Assembly 🔴 High Probability The IAT sensor is an integrated thermistor within the MAF assembly; internal failure of this component is common over time and mileage, creating an open circuit.
   How to confirm: Use a scan tool to view live data for the IAT sensor. A reading of -40°F or -40°C strongly indicates an open circuit, which is characteristic of a failed sensor. You can also test the sensor's resistance with a multimeter between the THA and E2G pins to see if it's within the specifications found in the factory service manual.
   Typical fix: Replace the entire Mass Air Flow sensor assembly. It is held in by two screws and is easily accessible on the air intake tube. 🎬 Watch this step-by-step walkthrough for replacing the Lexus ES350 sensor.
   Est. part cost: $150-$220
2. Damaged Wiring or Loose/Corroded Connector 🟡 Medium Probability This era of Toyota/Lexus vehicles used soy-based wiring insulation, which has been known to attract rodents that chew through wires, causing an open circuit.
   How to confirm: Visually inspect the wiring harness leading to the MAF sensor for any signs of fraying, melting, or rodent damage. Unplug the 5-pin connector and check for corrosion, moisture, or pushed-out pins. A multimeter can be used to check for continuity on the THA (IAT signal) and E2G (ground) wires between the sensor connector and the ECM.
   Typical fix: Repair the damaged section of wire or clean/replace the connector pigtail.
   Est. part cost: $10-$50
3. Dirty MAF/IAT Sensor Element ⚪ Low Probability Oil vapors from the PCV system or fine dust that gets past an aging or poorly-fitted air filter can coat the sensor elements over time.
   How to confirm: Remove the sensor and visually inspect the small wires and thermistor bulb inside the housing. If they appear coated in dirt or oil, cleaning is a worthwhile first step.
   Typical fix: Carefully spray the sensor elements with a dedicated Mass Air Flow sensor cleaner. Do not touch the elements with a brush, your fingers, or use aggressive cleaners like brake cleaner. 🎬 See how to safely clean your sensor without damaging it. Allow it to dry completely before reinstalling.
   Est. part cost: $10-$15

Rare But Worth Checking

• Faulty Engine Control Module (ECM): → Shop Engine Control Module (ECM) This is very uncommon. The ECM should only be considered after all other possibilities, including the sensor and wiring, have been thoroughly tested and ruled out.

Diagnosis Steps

1. Connect an OBD-II scanner and confirm P0113 is the active code. Check for any other codes, like P0102.
2. View the live data stream for 'Intake Air Temperature'. If it reads a static -40°F or -40°C, this confirms the ECM is seeing an open circuit.
3. Turn the ignition off and locate the MAF sensor on the air filter housing.
4. Inspect the electrical connector for a secure fit, corrosion, or damaged pins.
5. Inspect the wiring harness leading to the sensor for any visible damage, such as cracks, fraying, or signs of rodent activity.
6. If wiring looks good, remove the two screws holding the MAF sensor and carefully take it out.
7. Visually inspect the sensor elements. If they appear dirty, clean them with dedicated MAF sensor cleaner and let it dry completely. Reinstall, clear the code, and test drive to see if the code returns.
8. If cleaning does not work or the sensor was clean, replacement of the MAF assembly is the most likely fix.
9. For advanced diagnosis, if a new sensor does not resolve the code: Disconnect the sensor and turn the ignition ON. Use a multimeter to probe the harness-side connector. Check for a 5V reference signal on the THA wire and check for good ground on the E2G wire. An absence of either points to a wiring issue or a problem with the ECM.

Parts You'll Likely Need

• Mass Air Flow (MAF) Sensor (OEM #22204-31020) — This assembly contains the integrated IAT sensor that fails and causes the P0113 code. Replacing the entire unit is the standard repair. This part may be superseded by 22204-0P010.
  Trusted brands: Denso (OEM) - Part No. 197-6160
  OEM price range: $155-$215
  Aftermarket price range: $70-$150
• Mass Air Flow Sensor Cleaner — A low-cost first step. If the sensor elements are simply dirty, a cleaning may resolve the issue without needing to replace the part.
  Trusted brands: CRC, Liqui Moly
  Aftermarket price range: $10-$15
• MAF Sensor Connector Pigtail (OEM #90980-12292 (connector housing example)) — If the connector itself or the wires immediately attached to it are corroded or damaged, a new pigtail will be needed to ensure a solid connection to the new sensor.
  Trusted brands: Dorman, Standard Motor Products
  Aftermarket price range: $15-$40

Related Codes That Often Appear With This One

• P0102 — Mass Air Flow (MAF) Circuit Low Input. Since the IAT and MAF sensors are in the same housing, a bad connection, wiring damage, or a failing unit can cause both codes to appear together.
• P0335 — Crankshaft Position Sensor 'A' Circuit. In some no-start scenarios, a P0113 can appear alongside other circuit faults. It's important to diagnose the primary cause; in this case, a crank sensor fault would also prevent starting.

Technical Service Bulletins (TSBs) & Recalls

• No specific Technical Service Bulletins (TSBs) were found to directly address the P0113 code on this vehicle, as it is typically considered a standard component failure. However, class-action lawsuits have been filed against Toyota regarding rodent damage to soy-based wiring, which is a potential cause.

Platform-Specific Known Issues

• The use of soy-based wiring insulation in this generation of Toyota and Lexus vehicles can make the engine harness a target for rodents, potentially causing the open circuit that triggers a P0113 code. Inspection for chewed wires is recommended if the vehicle is parked outdoors.

Mechanic-Grade Diagnostic Values

• IAT Sensor Resistance — expected: Approximately 13.5 kOhms at -4°F (-20°C), 2.45 kOhms at 68°F (20°C), 0.32 kOhms at 176°F (80°C).. Failure: Infinite resistance (open circuit) or a reading that does not change with temperature indicates a failed sensor.
• IAT Sensor Signal Voltage (THA Pin at ECM) — expected: Varies with temperature, typically 0.2V (hot) to 4.8V (cold) with key on, engine off.. Failure: A static voltage at or near 5.0V indicates an open in the signal or ground circuit.
• Sensor Ground Voltage (E2G Pin at MAF Connector to Chassis Ground) — expected: Less than 100mV with key on, engine running.. Failure: Higher voltage indicates a poor ground connection between the sensor and the ECM, or a poor ECM ground.

Scan Tool Commands That Help

• Toyota Techstream: Data List -> Primary -> Intake Air — This is the primary method to confirm the fault. A reading of -40°F or -40°C is a definitive sign the ECM is seeing an open circuit, which triggers P0113.
• Toyota Techstream: Utility -> Monitor Status — Used to check the status of all system monitors after a repair to ensure the IAT circuit test will run and confirm the fix.

Wiring & Ground Locations

• MAF Connector (A41) — On the Mass Air Flow sensor, attached to the engine air filter housing.. This is the 5-pin connector housing the IAT signal (THA) and ground (E2G) wires. Corrosion or damage here is a common cause.
• ECM Pins THA & E2G — On the Engine Control Module (ECM). A wiring diagram shows THA at pin 73 and E2G at pin 72 of connector A55.. These are the termination points for the IAT circuit. Testing for continuity and voltage here can isolate a wiring problem from a sensor or ECM problem.
• ECM Grounds (E01, E02, E03, E04) — These are the main ground pins for the ECM, which are then connected to chassis ground points in the engine bay.. The sensor ground (E2G) relies on the ECM's main ground connection. A corroded or loose main ground point can cause a floating ground and trigger a P0113, even if the sensor and its direct wiring are good.

OEM Part Supersession History

• 22204-31020 → 22204-0P010, 22204-0T020, 22204-0V010 — Part revision and consolidation by the manufacturer.
• Denso (OEM Supplier) Aftermarket Part → 197-6160 — This is the direct aftermarket equivalent from the original manufacturer.
  Heads up: This is the most recommended replacement. Cross references include Delphi MF50073, ACDelco 213-4544, and Standard Ignition MAS0314.

Diagnostic Flowchart

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: A used OEM Denso MAF sensor from a reputable salvage yard can be a cost-effective option given the high price of a new OEM part. However, it is a gamble, as the part's remaining lifespan is unknown.

Donor-vehicle mileage cap: roughly under 80000 miles for the part to have meaningful remaining life.

What to inspect on the donor part:

• Inspect the sensor elements for physical damage or heavy contamination.
• Ensure the connector pins are straight and free of corrosion.
• If possible, get a part from a vehicle with a known history that was not involved in a flood or front-end collision.

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

• Mass Air Flow Sensor

Aftermarket brands forum-validated for this vehicle:

• Denso (This is the Original Equipment Manufacturer and is the most reliable choice).
• Hitachi (Also a known OEM supplier for many Japanese vehicles and generally considered reliable).

Brands owners have reported issues with on this vehicle:

• Unbranded, low-cost sensors from online marketplaces like eBay and Amazon are frequently counterfeit or of poor quality, often failing quickly or being dead-on-arrival.
• Store brands like Duralast have had reports of premature failure in this application.

Real Owner Stories

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

Related OBD-II Codes

• P0102 — Mass Air Flow (MAF) Circuit Low Input. This code is often seen with P0113 because the IAT sensor is physically integrated into the MAF sensor assembly. A wiring fault, bad connector, or internal failure of the assembly can trigger both MAF and IAT codes.
• P0101 — Mass Air Flow (MAF) Circuit Range/Performance. Can be triggered alongside P0113, particularly if an aftermarket air intake is installed, which can disrupt the calibrated airflow readings for both sensors.
• P0112 — Intake Air Temperature Sensor 1 Circuit Low. This is the direct companion code to P0113. While P0113 indicates a high input (open circuit), P0112 indicates a low input (short circuit), pointing to a fault in the same sensor or wiring.
• P0172 — System Too Rich (Bank 1). The P0113 fault causes the ECM to read an extremely cold -40° temperature, leading it to inject far too much fuel. This rich condition can be severe enough to trigger a fuel trim code.
• P0175 — System Too Rich (Bank 2). Similar to P0172, this code can be set on the second bank of the V6 engine due to the excessively rich fuel mixture commanded by the ECM in response to the false IAT sensor reading.

Frequently Asked Questions