P0133 Code: Toyota Camry (2018-2024) - Causes, Symptoms & Fixes

No recalls found in NHTSA database

In the NHTSA data you provided for Toyota Camry (2018-2024), there are no official recalls listed for this model year range. The owner complaint shown is for a different code (P0442), not P0133.

CODE MEANING AND SEVERITY

• What P0133 means: O2 Sensor Circuit Slow Response (Bank 1 Sensor 1). This is the upstream oxygen sensor (the sensor before the catalytic converter on Bank 1). The ECU expects a fast, responding signal from this sensor to adjust fuel trim. A slow or delayed response can cause improper air-fuel mixture and longer stabilization times for the ECU to adapt.
• Severity: Moderate. If left unresolved, the vehicle can experience degraded fuel economy, potential drivability issues under load, and higher emissions. In some cases the ECU may set other related codes (or the MIL may stay on) if the sensor remains slow to respond or fails to meet expected response times.

COMMON CAUSES ON TOYOTA CAMRY

• Faulty upstream O2 sensor (Bank 1 Sensor 1) itself
• Damaged or corroded wiring or connector to the upstream O2 sensor
• Exhaust leaks upstream of the sensor (manifold, gasket, or piping) causing false readings or slow sensor response
• Faulty or failing O2 sensor heater circuit (if equipped) leading to slow heating and delayed readings
• Vacuum leaks or unmetered air entering the intake (confounds O2 readings)
• Contamination on the sensor (oil/ coolant or silicone-based sealants) or improper sensor installation
• ECU/PCM software anomaly (rare; usually resolved with software updates or reprogramming)
• Aftertreatment or exhaust system issues that influence upstream sensor data indirectly

SYMPTOMS

• Check Engine Light (MIL) illuminated with P0133 stored
• Possible drop in fuel economy or unstable fuel trims
• Noticeable changes in acceleration or engine performance under varying loads
• Idle quality may be affected in some cases, but not always
• If another fault exists (engine misfire, vacuum leak, etc.), those symptoms may overshadow P0133
• In some cases, no obvious symptoms beyond the MIL

DIAGNOSTIC STEPS

Prepare and verify

• Use a high-quality OBD-II scanner to confirm P0133 and read freeze frame data (RPM, engine load, fuel trims, coolant temp, etc.).
• Record Short-Term Fuel Trim (STFT) and Long-Term Fuel Trim (LTFT) values for Bank 1 Sensor 1, at idle and at operating temp.
• Check for any related codes (P0130, P0131, P0132, P0134, P0135-P0139, etc.) and any misfire codes.

Inspect the hardware

• Visually inspect Bank 1 Sensor 1 upstream O2 sensor and wiring harness for obvious damage, corrosion, or disconnection.
• Check the electrical connector pins for bent pins, corrosion, or loose connection; reseat and clean if necessary.
• Look for exhaust leaks upstream of the sensor (manifold gaskets, EGR area, or pipe joints). Even small leaks can cause erratic readings.
• Inspect for oil/oil vapor or coolant contamination on the sensor or its wiring.

Check the sensor and heater circuit

• If the vehicle has a heated O2 sensor, test the heater circuit: measure resistance across the heater pins or use the scan tool to check heater operation. Compare to the manufacturer spec.
• Verify power and ground at the sensor connector with a multimeter when the engine is at operating temperature.

Compare with downstream sensor

• Monitor Bank 1 Sensor 2 (catalytic converter outlet) live data while driving. If Sensor 2 shows a rapid and reasonable response but Sensor 1 is slow to respond, the issue is more likely the upstream sensor or upstream conditions (not the catalytic converter).
• Look for wide lean/rich trends (STFT/LTFT) that coincide with the slow upstream sensor signal.

look for related engine/system conditions

• Check for vacuum leaks using a smoke test or a spray test around intake manifold, throttle body, PCV, and vacuum hoses.
• Check for misfire conditions or a clogged injector that could skew readings and create false slow-response data.
• Inspect intake air system and MAF sensor for cleanliness and proper readings.

Functional tests

• If feasible, perform a controlled test drive to observe the O2 sensor response time. Compare the upstream sensor's voltage swing (roughly 0.1–0.9 V range) and its speed to the downstream sensor.

Decision point

• If wiring and harness are intact and there are no leaks, and the upstream sensor heater works but the signal remains slow, replace Bank 1 Sensor 1 upstream O2 sensor.
• If the sensor replacement does not resolve P0133, re-check for leaks or exhaust issues, and consider additional diagnosis of related systems (vacuum, MAF, PCV, or a software reflash if indicated by a Toyota bulletin or PCM compatibility issue).

After repair

• Clear codes and perform a road test to verify no reoccurrence of P0133.
• Confirm successful sensor readings: stable STFT/LTFT within expected ranges and a healthy switch of O2 sensor voltages.

RELATED CODES

• P0130 O2 Sensor Circuit Malfunction (Bank 1 Sensor 1) — general O2 sensor circuit problem
• P0131 O2 Sensor Circuit Low Voltage (Bank 1 Sensor 1)
• P0132 O2 Sensor Circuit High Voltage (Bank 1 Sensor 1)
• P0134 O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 1)
• P0135-P0139 variants (O2 sensor/heater circuit issues for Bank 1 Sensor 1 or 2)
• P0171/P0174 System Too Lean or Rich (if persistent after sensor work)
  Note: P0133 is specifically about a slow response on Bank 1 Sensor 1; other codes may point to related sensor circuits or downstream effects.

REPAIR OPTIONS AND COSTS (2025 prices)

• Upstream O2 sensor replacement (Bank 1 Sensor 1)

  • Parts: $40–$150 (aftermarket) or $120–$300+ (OEM/Toyota)
  • Labor: $75–$180 (depends on shop rates and access on Camry)
  • Typical total: $120–$380
  • Notes: Access, mounting location, and sensor type affect labor time. Toyota sensors sometimes include anti-seize on threads; follow the manufacturer’s guidance during installation.

• Wiring harness/connector repair

  • Parts: $20–$100 (depending on extent of damage)
  • Labor: $60–$150
  • Typical total: $100–$250
  • Notes: If harness damage is extensive, replacing the entire harness section or using a repaired pigtail may be needed.

• Exhaust leak repair (before the sensor)

  • Parts: $20–$200 (gaskets, clamps)
  • Labor: $100–$300
  • Typical total: $120–$500
  • Notes: A leak upstream of the sensor can cause erroneous readings; fixing the leak may resolve P0133 without replacing the sensor.

• Catalytic converter-related repairs (less common for P0133 alone)

  • Parts: $500–$2,000+ (depending on converter)
  • Labor: $150–$500
  • Typical total: $650–$2,500+
  • Notes: Considered only if converter or downstream sensor issues are confirmed.

• Replacing downstream sensor or software update (if indicated)

  • Downstream Sensor 2 replacement: $100–$300 parts, $80–$150 labor
  • Software update/ECU reflash: $0–$150 depending on dealer/independent shop
  • Typical total: $180–$450

DIAGNOSIS DATA LIMITATIONS

• The provided NHTSA data shows no P0133 complaints in the Camry (2018-2024) and no recalls for this model year range. The only listed complaint is for P0442 (gas cap-related), not P0133. This guide reflects general automotive knowledge and typical Camry experience with P0133, but it is not based onCamry-specific NHTSA complaint statistics for this code.
• If you are diagnosing in the real world, rely on live scan data, wear patterns on the sensor, and local vehicle history to determine the exact cause.

DIY vs PROFESSIONAL

• DIY (Moderate risk, if you have tools and comfort with automotive electrical systems)

  • Pros: Cost savings, educational experience
  • Cons: Access to upstream O2 sensor on some Camry models can be challenging; risk of damaging wiring or sensor; ensure you use proper O2 sensor socket and tip-friendly removal technique; avoid contaminating the new sensor with oil/grease.

• Professional (Recommended for most Camry owners)

  • Pros: Accurate diagnosis with live data, proper handling of sensors and exhaust system, guaranteed parts and labor
  • Cons: Higher upfront cost

• If you have DIY experience, a common approach is to replace the upstream O2 sensor first and then test drive; if the code persists, proceed with a more thorough inspection of wiring and exhaust leaks.

PREVENTION

• Regular maintenance and timely repairs to avoid exhaust leaks and sensor contamination
• Use good quality fuel and automotive detergents to keep the engine and sensors clean
• Schedule periodic inspections of the exhaust system, especially around the manifolds and pre-cat areas
• Avoid silicone sealants near oxygen sensor installation areas and ensure sensors are properly torqued to specification
• Address idle/unmetered air leaks promptly (PCV hoses, vacuum lines)
• If you notice a recurring MIL with P0133, address the issue promptly to prevent potential catalyst efficiency issues or fuel economy loss

Final notes

• If you’re dealing with P0133 on a 2018-2024 Toyota Camry, start with a thorough inspection of the upstream O2 sensor and its wiring, plus any exhaust leaks upstream of the sensor. Replacing the upstream sensor is a common and often effective first step, but verify that wiring, connectors, and exhaust integrity are sound to avoid repeat failures. Always clear codes after repairs and perform a thorough test drive to confirm the issue is resolved. The data provided for recalls does not indicate any official recalls related to this DTC in the given dataset. If your vehicle exhibits persistent symptoms or you have access to Toyota-specific service bulletins, consult those resources for any model-year-specific guidance.