P0117 on 2006-2012 Toyota RAV4: Engine Coolant Temperature Sensor Causes and Fixes

What's Unique About the 2006-2012 Toyota RAV4

For the third-generation RAV4 (XA30), this code is a very common and straightforward issue. Both the 2AZ-FE and 2GR-FE engines use a simple two-wire thermistor sensor that is known to fail over time by shorting internally. Unlike more complex diagnostic codes, P0117 on this platform rarely points to a deeper systemic issue; owner and technician experiences overwhelmingly indicate the sensor itself is the point of failure. Access is relatively easy on both engines, following the upper radiator hose to the thermostat housing.

Symptoms You May Notice

• Check Engine Light is on
• Engine cooling fans run continuously, even when the engine is cold
• Temperature gauge on the dashboard reads unusually high, is maxed out, or blinking
• Engine is difficult to start, especially when cold
• Rough or unstable idle
• Noticeably reduced fuel economy
• Black smoke from the exhaust due to a rich fuel mixture
• A/C may not blow cold as the system prioritizes engine protection

Most Likely Causes

1. Defective Engine Coolant Temperature (ECT) Sensor 🔴 High Probability → Shop Engine Coolant Temperature Sensor The internal thermistor in the sensor can degrade over time, leading to an internal short circuit that produces the low voltage signal. It is a widely used part across many Toyota models and is a common failure item.
   How to confirm: With the engine cold, use an OBD-II scanner to view live data. If the coolant temperature reads an impossibly high value (like 140°C / 284°F), the sensor is bad. You can also test the sensor's resistance with a multimeter. 🎬 Watch: How to test and replace your coolant temperature sensor It should be around 2,000-3,000 Ω at 68°F (20°C). A reading of near-zero ohms indicates a shorted sensor.
   Typical fix: Replace the Engine Coolant Temperature sensor. This is a single component held in by a clip or threaded into the thermostat housing. On the 2GR-FE V6, it's a 19mm or 3/4" deep socket.
   Est. part cost: $20-$80
2. Damaged Wiring or Connector 🟡 Medium Probability The wiring harness near the engine is exposed to heat and vibration, which can cause wires to fray, insulation to crack, or the connector to become corroded or loose over time. Sometimes the connector tab breaks, leading to a poor connection.
   How to confirm: Visually inspect the two-wire harness leading to the ECT sensor for any signs of cracking, melting, or corrosion. Wiggle the connector and harness with the engine running to see if the temperature reading on a scan tool fluctuates. Check for a short to ground using a multimeter. You can also jump the two pins on the connector with a paperclip; the scan tool reading should change from extremely low (-40°F) to extremely high (284°F+), which confirms the wiring to the ECM is good.
   Typical fix: Repair the damaged section of wire or replace the pigtail connector.
   Est. part cost: $10-$30
3. Low Engine Coolant or Air in the System ⚪ Low Probability → Shop Engine Coolant / Antifreeze While more likely to cause a P0115 or P0118 code, a large air pocket trapped around the sensor can cause it to send erratic signals. A severe overheating event from low coolant could also damage the sensor, leading to a P0117.
   How to confirm: Check the coolant level in the radiator (when the engine is cold) and the overflow reservoir. If low, top it off and properly bleed the cooling system to remove any trapped air.
   Typical fix: Top off and bleed the cooling system. If the code persists, the sensor was likely damaged by the prior condition and still needs replacement.
   Est. part cost: $15-$30 for coolant

Rare But Worth Checking

• Faulty Engine Control Module (ECM): → Shop Engine Control Module (ECM) This is extremely rare. Before condemning the ECM, all other possibilities (sensor, wiring, coolant level) must be exhaustively ruled out. An ECM failure is the cause in less than 1% of cases for this code.

Diagnosis Steps

1. Connect an OBD-II scanner and confirm P0117 is the active code. 🎬 See two quick DIY methods to fix the P0117 code Note any other codes.
2. View the live data stream for the Engine Coolant Temperature (ECT). If it shows an extremely high value (e.g., 284°F / 140°C) on a cold engine, the sensor or its circuit is shorted.
3. Turn the engine off. Locate the ECT sensor. On both the 2AZ-FE (4-cyl) and 2GR-FE (V6), follow the upper radiator hose to where it connects to the engine; the sensor is on the thermostat housing.
4. Inspect the sensor's electrical connector and nearby wiring for any visible damage, corrosion, or loose connections.
5. Disconnect the ECT sensor. With the key on and engine off, check the live data again. The temperature reading should now show an extremely low value (e.g., -40°F / -40°C) and may set a P0118 code. If it does, this confirms the wiring to the ECM is likely okay and the original sensor is faulty.
6. (Optional Wiring Test) If the reading does not change or remains high after disconnecting, check the wiring harness for a short to ground between the sensor connector and the ECM. A 'bridge' test using a paperclip to connect the two terminals in the harness connector should make the scan tool reading jump to maximum temperature, confirming the circuit integrity.
7. If wiring is confirmed good, replace the ECT sensor. A small amount of coolant may leak out. Have the new sensor ready to swap in quickly to minimize loss.
8. After replacement, top off any lost coolant, clear the codes with the scanner, and perform a test drive to ensure the temperature gauge reads normally and the code does not return.

Parts You'll Likely Need

• Engine Coolant Temperature Sensor (OEM #89422-33030) — This sensor is the primary cause of code P0117 on this vehicle due to internal failure over time. This part number is widely used across many Toyota, Lexus, and Scion vehicles.
  Trusted brands: Denso (OEM manufacturer), Aisin, Standard Motor Products (SMP), Beck/Arnley
  OEM price range: $45-$85
  Aftermarket price range: $20-$50

Related Codes That Often Appear With This One

• P0118 — If there is an intermittent short and open in the same circuit, you might see P0118 (Circuit High) stored along with P0117. This strongly points to a wiring or connector problem.
• P0115 — This is a general ECT circuit malfunction code. It can appear alongside P0117 if the signal is erratic before failing completely to a 'low' state.

Platform-Specific Known Issues

• Sensor Location and Access: On the 2AZ-FE (2.4L), the sensor is relatively open and easy to access near the top of the engine. 🎬 Watch this walkthrough for replacing the sensor on Toyota engines On the 2GR-FE (3.5L V6), it is in a similar location on the thermostat housing but may be slightly more difficult to reach due to engine covers and intake components. On the V6, a 19mm or 3/4" deep socket is required. For those with large hands, removing the airbox may provide better access.
• Owner Experience: Quick Fix: Multiple owners on forums like RAV4World and Toyota Nation report that this is one of the easiest codes to fix. A common story involves the temperature gauge suddenly maxing out, the fans running constantly, and a quick 15-minute sensor swap resolving all symptoms permanently.

Mechanic-Grade Diagnostic Values

• ECT Sensor Resistance vs. Temperature — expected: At 20°C (68°F): 2,200 - 3,000 Ω. At 80°C (176°F): 250 - 350 Ω. At 100°C (212°F): 180 - 250 Ω.. Failure: A resistance reading near zero ohms indicates a shorted sensor, causing P0117. An infinitely high reading (open circuit) would cause P0118.
• ECT Sensor Voltage at ECM (2AZ-FE Engine) — expected: At 80°C (176°F), the voltage between terminals THW and ETHW should be 0.2V to 1.0V.. Failure: A voltage below 0.14V for more than 0.5 seconds will trigger the P0117 code.

Hidden / Shadow Codes Worth Checking

• N/A (Live Data Anomaly): Toyota's Techstream software doesn't use a hidden code but will display a specific, impossible temperature value in the live data list. For a P0117 (short circuit), the 'Coolant Temp' will read 140°C (284°F) or higher. For the opposite code, P0118 (open circuit), it will read -40°C (-40°F). (see via Using Toyota Techstream or a compatible high-end scan tool, navigate to: Powertrain / Engine and ECT / Data List / Coolant Temp.)

Scan Tool Commands That Help

• Toyota Techstream: Data List > Coolant Temp — This is the primary diagnostic step. Instead of an active test, a technician immediately checks this live data parameter. Seeing a value of 140°C on a cold engine instantly confirms a shorted sensor or circuit, which is the direct cause of P0117.

Wiring & Ground Locations

• ECM Terminals (2AZ-FE) — At the main Engine Control Module (ECM).. For testing the circuit directly at the computer, the ECT sensor connects to terminals THW (Signal, Green wire) and ETHW (Ground, Brown wire). This allows a technician to verify if the short is in the harness or internal to the ECM.
• Engine Ground Points (General) — Key grounds are typically bolted to the cylinder head, the engine block (often near the intake manifold), and from the block/transmission to the firewall or chassis rail.. The ETHW terminal provides the sensor ground reference back to the ECM. While a faulty ground point specific to only the ECT is unlikely, a corroded main engine ground can cause multiple, erratic sensor issues. Verifying the main grounds are clean and tight is a good practice if other codes are present.

OEM Part Supersession History

• 89422-33030 → 89422-33030 — This part number has remained stable and is used across a vast range of Toyota, Lexus, and Scion models for many years. No significant supersessions noted for this vehicle generation.

Model Year Variations Within This Range

• 2006-2008: These years used the 2.4L 2AZ-FE 4-cylinder engine.
• 2009-2012: These years received a facelift and the 4-cylinder engine was upgraded to the 2.5L 2AR-FE. The 3.5L 2GR-FE V6 was available throughout the entire 2006-2012 period. The diagnostic procedure for P0117 remains the same across all engines, but component layout around the sensor may vary slightly.

Diagnostic Flowchart

Other Known Issues on This Vehicle

Issues unrelated to this code that are worth knowing about as an owner of this generation:

• Excessive Oil Consumption (2AZ-FE) 🔴 High — Very common, particularly in 2006-2008 models. Can start as early as 60,000 miles and worsens over time. (Ref: TSB Z-T-SB-0094-11 (Piston assembly changed to minimize consumption))
• Rupturing VVT-i Oil Line (2GR-FE) 🔴 High — Common on 2006-2009 V6 models. The original rubber hose section degrades and can burst, causing rapid and catastrophic oil loss. (Ref: LSC (Limited Service Campaign) 90K, extended to March 31, 2013. Replaced rubber/metal line with an all-metal line (Part No. 15772-31030).)
• Steering Intermediate Shaft Clunk/Pop 🟠 Medium — Extremely common across all 2006-2012 models. A popping or clunking noise is heard/felt in the steering wheel at low speeds. (Ref: TSB T-SB-0033-11 (Supersedes T-SB-0318-08). Recommends replacing the shaft with an updated part (Part No. 45260-42090).)
• Water Pump Failure (2GR-FE) 🟠 Medium → Shop Engine Water Pump — A known weak point on the V6 engine, often failing between 80,000-160,000 miles. Symptoms include a whining noise and coolant leaks from the weep hole.

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: For this specific repair, a used part is not recommended. The ECT sensor is an inexpensive wear item, and the labor to replace it outweighs the small cost savings. The age and condition of a used sensor are unknown, and it may fail shortly after installation.

What to inspect on the donor part:

• Not applicable as a used part is not advised.

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

• Engine Coolant Temperature Sensor

Aftermarket brands forum-validated for this vehicle:

• Denso (This is the Original Equipment Manufacturer for Toyota, buying Denso is equivalent to buying the genuine Toyota part without the dealer markup).
• Aisin

Brands owners have reported issues with on this vehicle:

• Generic, unbranded, or 'white-box' sensors from online marketplaces. Forum discussions frequently warn that cheap aftermarket sensors can be inaccurate out of the box or fail prematurely, causing the code to return.

Real Owner Stories

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

Related OBD-II Codes

• P0118 — This code represents the opposite condition (Engine Coolant Temperature Circuit High Input). It often appears during diagnosis if the ECT sensor is disconnected while the key is on.
• P0115 — A related Engine Coolant Temperature circuit malfunction code that can be triggered by air pockets or low coolant levels in the system.

Frequently Asked Questions