P0051 on Lexus: Causes, Symptoms and Fix Cost
Quick Answer
Safe to drive (short-term)
P0051 on a Lexus means the engine computer sees too little current in the heater of the front oxygen sensor on bank 2, the side of a V or flat engine that does not hold cylinder 1. Only engines with two cylinder banks can set it. The heater brings the sensor to working temperature quickly after a cold start, and without it the mixture runs on fixed values for longer. The usual causes are a burned-out heater, an open wire, or a failed sensor relay or fuse. A new front sensor on this bank typically costs 130 to 400 EUR fitted.
- Severity
- Low · Emissions
- Typical repair cost, all makes
- €1-€400
Connect a standard OBD2 adapter (Bluetooth LE on iPhone) to your Lexus and Skanyx tells you what P0051 means on that engine, whether it is safe to keep driving, and what the fix should cost. Free on iPhone and Android.
Get Skanyx freeWhat does P0051 mean on a Lexus?
The Quick Answer above is the generic definition. What follows is the model-specific detail for the Lexus models that log P0051.
Lexus ES 350 (3.5 V6)
2007-2012
Toyota's information for the 2GR-FE 3.5 V6 in the ES 350 reads P0051 as A/F Sensor Heater Control Circuit Low (B2S1), set when heater current is below 0.8 A, and gives a heater resistance of 1.8 to 3.4 ohms. A published case on a 2007 ES 350 with a replacement engine went through two sensors and three computers before a missing ground at the engine computer was found, so test grounds before buying a computer.
Source: automotivetechinfo.com, en.wikipedia.org
Sources
- automotivetechinfo.com automotivetechinfo.com/2021/12/the-sad-saga-of-the-2007-lexus-es350-and-a-p0051-
- en.wikipedia.org en.wikipedia.org/wiki/Lexus_ES
What causes P0051 on a Lexus?
Beyond the generic causes listed on the main P0051 page, these are the patterns noted for Lexus models:
Open heater circuit or failed air-fuel sensor heater
: Lexus ES 350 (3.5 V6)
Missing ground at the engine computer for the heater driver
: Lexus ES 350 (3.5 V6)
How to diagnose P0051 on a Lexus with OBD2
- Confirm which side is bank 2. It is the cylinder bank that does not contain cylinder 1, so the owner's manual or an engine diagram decides it, not left or right. Check that the code is not stored together with a bank 1 heater code, which would point to a shared fuse or relay
- Find the sensor heater fuse and relay in the fuse box diagram and test them. A fuse that keeps blowing means a short in the heater or its wire
- Unplug the bank 2 front sensor and measure the resistance across the two heater pins against the maker's value. One Toyota procedure for a V6 gives 1.8 to 3.4 ohms; other makes differ, so use your car's figure. An open circuit means the heater has failed
- With the key on, check for supply voltage on the heater power pin of the harness plug. No voltage points to the fuse, relay or supply wire
- Check continuity of the heater control wire from the sensor plug to the engine computer, and look for chafing, melted insulation or pins pushed back in the connector
- If sensor and wiring test good, check every ground that serves the engine computer before condemning it. In a published case on a Lexus ES 350 V6, P0051 survived two new sensors and three replacement computers until a missing ground at the engine computer was found
- After the repair, clear the code, do a cold start and a normal drive, and use a generic reader to confirm the heater monitor completes and the fuel system reaches closed loop
How much does P0051 cost to fix on a Lexus? (EUR)
Estimated repair costs for P0051 in EUR, compiled across makes. Expect Lexus parts and labour towards the upper end of each range.
| Repair | Parts Cost | Labor Cost | Total Estimate | DIY Difficulty |
|---|---|---|---|---|
| Replace sensor heater fuse | €1–€3 | €0–€0 | €1–€3 | Easy |
| Replace sensor heater relay | €10–€40 | €20–€60 | €30–€100 | Easy |
| Repair wiring or connector | €5–€20 | €40–€120 | €45–€140 | Moderate |
| Replace front air-fuel or oxygen sensor (Bank 2) | €80–€300 | €50–€100 | €130–€400 | Moderate |
| Workshop circuit diagnosis (power, ground and heater current) | €0–€0 | €60–€120 | €60–€120 | Professional |
Prices estimated as of October 2026. Costs vary by region, vehicle, and shop.
Codes related to P0051
These codes are often seen alongside P0051 or point to related issues, on any make:
Looking for the full P0051 reference (all makes, full diagnosis flow, complete repair cost matrix)? See the main P0051 guide