P0136: O2 Sensor Circuit Bank 1 Sensor 2
A generic powertrain (engine and transmission) trouble code, same meaning on every brand.
Yes - this sensor monitors the catalytic converter and does not control fuelling.
Symptoms
- Check engine light only
- No change in how the car drives
- Emissions test failure
Likely causes, most common first
- Downstream oxygen sensor failed
- Wiring damaged by road debris or corrosion
- Exhaust leak after the catalytic converter
- Sensor contaminated by burnt oil or coolant
Read P0136 yourself before paying for diagnosis
A basic Bluetooth OBD-II scanner ($20-40) plugs into the port under the dashboard and shows this code with live sensor data on your phone - useful both for confirming the fix and for talking to a shop from an informed position.
What is going on and how it gets diagnosed
P0136 concerns the sensor behind the catalytic converter on bank 1. Its job is to grade the converter's work, not to control the engine, which is why the car usually drives exactly as before and only the light gives it away.
The downstream sensor lives under the car where salt, water and stones reach it, so its wiring fails more often than the wiring of the upstream sensor. Inspect the harness along its whole run before ordering a part - a chafed wire against the floorpan is a common and cheap find.
Repair options and cost
Typical US independent-shop ranges, parts and labor. Dealers run higher; regional labor rates vary.
Owner reports mentioning P0136
“Reporting - safety recall as stated on NY state fail inspection. Emissions issues Ãmission results- MIL commanded "fail" Code P0136-O2 Sensor Code PO455 -Evaporative emission system leak”2001 Mitsubishi Montero · Jun 2022
“I keep getting a p0136 bank 1 sensor 2 error code. Took it to several mechanics and they switched the 02 censor (downstream). Also shows that bank 1 sensor 2 has 0% voltage. Unplugged the downstream 02 sensor and got a reading but no reading when plugged in. Checked wiring harness to ecm and everything was fine. Both mechanics have determined that the issue is with the ecm. My vehicle has roughly about 70k miles on it. My car will not pass smog until this is fixed. Mechanic is recommending reflashing ecm or replacing it. P0136 comes up as pending and will stay permanent on the second drive cycle. Check engine light stays on.”2013 Toyota Prius · Nov 2020 · 78,352 mi
“Check engine light came on. Dealer diagnostic report showed a failure code of p0136 oxygen sensor malfunction. Dealer advised that sensor should be replaced at a cost of $230.00. If part was not replaced the engine or emissions system could be damaged, and the car unsafe to drive due to possible failure while driving.*ak”2004 Toyota Camry · Jun 2007 · 44,101 mi
Cars that report P0136 most often
Based on mentions of this code in NHTSA owner complaints.
Frequently asked questions
Can I drive with P0136?
Yes - this sensor monitors the catalytic converter and does not control fuelling.
How much does it cost to fix P0136?
Typical US repair costs range from $80 for the simplest fix (downstream oxygen sensor) to $600 in the worst case. The right number depends on which cause your car has - see the causes list.
Related codes
The codes closest to P0136. They often appear together, and telling them apart is usually what narrows the diagnosis.
Definition per SAE J2012 standard nomenclature. Symptoms, causes and costs are editorial guidance - always confirm with a diagnosis of your specific vehicle.