P0136: Rear oxygen sensor circuit fault (bank 1, sensor 2)
O2 sensor circuit, bank 1 sensor 2 (downstream)
Severity: Monitor
Kelley Blue Book rates the code moderate: the car can be driven but the fault should be repaired, since a failed sensor can leave the engine running badly over time.
It gets more serious if:
- Inspect soon: Inspect soon if the engine runs rough, runs rich or loses power, which Kelley Blue Book lists as possible symptoms.
P0136 in short
P0136 means the oxygen sensor behind the catalytic converter on bank 1 is not working correctly. A worn sensor, damaged wiring or an exhaust leak near the sensor is usually the reason. The car normally drives as usual, so it is safe to drive to a shop, but fix it soon.
Cars have an oxygen sensor ahead of the catalytic converter and one behind it. P0136 is for the one behind the converter on bank 1, sensor 2. The computer expects its reading to be steady and different from the front sensor. If the circuit or signal is faulty, it sets P0136.
Kelley Blue Book lists a failed sensor, an exhaust leak near it, corroded connectors or wiring and open or shorted circuits. Toyota has several bulletins for P0136 on the Tacoma, 4Runner and Prius, and for the Land Cruiser an engine computer calibration update.
On a 2013 Prius owner's complaint, the code stayed after the downstream sensor was replaced, so an unchanged code after a new sensor should send the search back to the wiring and connector.
Most likely causes
Cause 1: Rear oxygen sensor failed
Common general cause- Why it ranks here
- Kelley Blue Book lists a faulty sensor first. A 2004 Camry dealer readout of P0136 advised replacing the sensor.
- What would change this
- Rises if wiring tests good and the sensor signal is dead or stuck. Falls if the circuit is faulty or the code returns after a new sensor.
Cause 2: Exhaust leak near the sensor
Common general cause- Why it ranks here
- Kelley Blue Book lists exhaust leaks near the sensor as a cause.
- What would change this
- Rises if soot or a hissing leak is found by the sensor. Falls if the exhaust is tight.
Cause 3: Corroded or damaged connector or wiring
Common general cause- Why it ranks here
- Kelley Blue Book lists corrosion and open or shorted wiring. A Prius owner kept the code after a sensor swap with the sensor reading 0 volts.
- What would change this
- Rises if the connector is damaged or the signal wire reads open. Falls if the circuit tests good.
Cause 4: Engine computer calibration (some Toyotas)
Supported by vehicle data- Why it ranks here
- Toyota's Land Cruiser bulletin 04605 updates the engine computer calibration for MIL with P0136 or P0156, and bulletins 02302 and 00505 also cover P0136 on other Toyota models. Both are unverified summaries.
- What would change this
- Rises on a covered Toyota when the computer is not at the latest calibration. Falls if it is current.
What to test first
Start at step 1. Each result tells you what it means and where to go next.
Step 1: Read all stored codes and freeze-frame data. Note any catalyst code (P0420) or other oxygen sensor code stored with P0136.
IfP0420 or other O2 codes are also stored
It meansMention them all; the rear sensor and the converter are checked together.
IfP0136 is the only code
It meansInspect the sensor wiring and exhaust.
Step 2: With the engine off and cool, look at the rear sensor wire, connector and the exhaust joints around it for damage, corrosion, soot or a leak.
Warning:The exhaust pipes and converter stay hot after driving. Let them cool fully first.
IfA damaged wire or connector is found
It meansRepair the circuit.
IfA leak or soot trail is found at the sensor
It meansRepair the leak.
IfNothing is found
It meansTest the sensor with a scan tool.
Step 3: Watch the rear sensor reading with a scan tool and test the circuit; also ask a dealer whether a calibration update applies to your Toyota.
Warning:Needs a professional shop with the right scan tool and wiring diagrams; do not guess at this step.
IfThe reading is stuck or flat and the circuit is good
It meansThe sensor is the likely fault.
IfA calibration update applies and is not installed
It meansInstall the update first.
Symptoms
- Check engine light on
- Usually no change in how the car drives
- Rough idle or weaker acceleration in some reports Gets more serious: stop and have it checked.
How to fix
Step 1: With the engine off and cool, look at the rear oxygen sensor wire and plug for damage, and listen for an exhaust leak near the converter when the engine is first started.
Parts and cost context
- Oxygen (O2) sensor:The rear sensor is after the catalytic converter; check the wiring and exhaust before buying one. Labor varies; get a quote.
Labor varies by vehicle and shop; get a quote before you approve a repair.
Compare used part prices on PartPriceGuideOn your vehicle
ToyotaYour car
2004–2013 · Prius
Supported by vehicle dataToyota bulletin 01803 covers the 2004 Prius with P0136 and/or P0138. A 2013 Prius owner reports the code staying after a downstream sensor swap. Whether the bulletin is still current is not verified.
2002 · Tacoma
Supported by vehicle dataToyota bulletin 02302 covers MIL with P0136 on the 2002 Tacoma. The NHTSA summary does not give the repair.
2004 · Camry
Possible — needs testingA 2004 Camry owner reports a dealer readout of P0136 with advice to replace the oxygen sensor.
02302Status unverified
MIL on with P0136 stored
2002tacoma · NHTSA 10000658
NHTSA summary only; it does not give the repair.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
00505Status unverified
MIL on with P0136 and/or P0156
2003–20044runner · NHTSA 10015535
NHTSA summary only; it does not give the repair.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
01803Status unverified
MIL on with P0136 and/or P0138
2004prius · NHTSA 10005833
NHTSA summary only; it replaces an earlier bulletin 01803R.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
04605Status unverified
ECM calibration update, MIL on with P0136 and/or P0156
2004–2005land-cruiser · NHTSA 10017641
Updates the engine computer calibration.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
FordYour car
1999 · Mustang
Possible — needs testingFord bulletin 8043 lists P0136 with P0141, P0156 and P0161 on the 4.6L 2V engine. The summary does not give the repair.
8043Status unverified
4.6L 2V engine with P0136, P0141, P0156, P0161
1999mustang · NHTSA 612243
NHTSA summary lists the codes only; it does not give the repair.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
Related codes
P0136 questions
Will a new rear oxygen sensor fix P0136?
Often, but not always. A Prius owner kept the code after a sensor swap, so check the wiring and exhaust first.
Is P0136 the same as a bad catalytic converter?
No. P0136 is a sensor circuit fault. A converter fault sets a different code such as P0420.
Sources and review
- P0136 O2 sensor circuit, bank 1 sensor 2
- NHTSA complaint ODI 10194123, 2004 Toyota Camry: dealer read P0136 oxygen sensor malfunction and advised replacing the sensor
- NHTSA complaint ODI 11377970, 2013 Toyota Prius: P0136 with bank 1 sensor 2 reading 0 volts, persisted after a downstream sensor was replaced
- Toyota bulletin 02302: MIL on with P0136 stored, 2002 Tacoma
- Toyota bulletin 00505: MIL on with P0136 and/or P0156, 2003-2004 4Runner
- Toyota bulletin 04605: ECM calibration update for MIL on with P0136 and/or P0156, 2004-2005 Land Cruiser
- Toyota bulletin 01803: MIL on with P0136 and/or P0138, 2004 Prius
- Ford bulletin 8043: 1999 Mustang 4.6L 2V with P0136, P0141, P0156, P0161
- Last reviewed
- Written by
- Saurabh K.
- Editorial review
- Pending
- Technician review
- Technician review pending
This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error