P2255 — O2 Sensor Negative Current Control Circuit Low Bank 2 Sensor 1

P2255 — O2 Sensor Negative Current Control Circuit Low Bank 2 Sensor 1. A fault in the oxygen sensor circuit. The car is usually drivable while you plan the repair. Typical causes: aged or contaminated oxygen sensor, exhaust leak near the sensor, oil or coolant contamination of the sensor tip.

powertrain (engine/transmission)

Is it safe to drive?

Short-term driving is OK You can usually drive for a while: the engine runs on a default fuel strategy, which costs you fuel and emissions. Fix it soon — prolonged driving with a bad O2 sensor can overheat and damage the catalytic converter.

How to diagnose with an OBD scanner

Read the code and freeze frame Connect an OBD2 scanner, confirm P2255 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
Check for companion codes and TSBs Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many P0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
Inspect wiring and connectors Visually inspect the wiring harness and connectors related to the oxygen sensor circuit for damage, corrosion, chafing or poor contact.
Subsystem check Watch the sensor voltage in live data: a healthy upstream sensor switches rapidly between roughly 0.1 and 0.9 V.
Subsystem check Measure heater resistance on the sensor connector and check the heater fuse and relay.
Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm P2255 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for P2255 (parts and labor, USD, independent shop rates): Repair sensor wiring: $80–$250; Replace the oxygen sensor: $150–$450; Fix an exhaust leak near the sensor: $100–$300. Overall, fixing P2255 usually costs between $80 and $450. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Common questions

What is the most common cause of P2255?

The most common causes are: aged or contaminated oxygen sensor, exhaust leak near the sensor, oil or coolant contamination of the sensor tip.

What does OBD2 code P2255 mean?

How do I diagnose P2255 myself?

Start with a scan: confirm P2255, save the freeze frame and note any companion codes. Then inspect the wiring and connectors related to the oxygen sensor circuit, and verify the suspect component against live data before buying parts.

What are the symptoms of P2255?

Drivers most often notice: rough idle, Check Engine Light on, sluggish throttle response, failed emissions test.

Is it safe to drive with P2255?

You can usually drive for a while: the engine runs on a default fuel strategy, which costs you fuel and emissions. Fix it soon — prolonged driving with a bad O2 sensor can overheat and damage the catalytic converter.

What does P2255 mean?

Seeing P2255 on your scanner? The control unit has caught the oxygen sensor circuit operating outside its calibrated window. The formal description is “O2 Sensor Negative Current Control Circuit Low Bank 2 Sensor 1”, and the code is grouped under powertrain (engine/transmission) faults.

In this definition, “Bank 2” is the side of the engine opposite to cylinder 1 and “Sensor 1” is the upstream (before the catalytic converter) sensor. Mixing up banks and sensor positions is the most common DIY mistake with this code — verify the physical location before replacing anything.

The module monitors this system continuously while driving. When readings fall outside the expected range for a defined number of drive cycles, it stores P2255 and switches on the warning light. Freeze frame data saved with the code shows the exact conditions — rpm, load, temperature, speed — at the moment the fault was detected, which is the best starting point for diagnosis.

What causes P2255?

aged or contaminated oxygen sensor
damaged sensor wiring or connector
ECM signal circuit fault
oil or coolant contamination of the sensor tip

Common symptoms of P2255

rough idle
Check Engine Light on
sluggish throttle response
failed emissions test
increased fuel consumption

How to diagnose P2255

Connect an OBD2 scanner, confirm P2255 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many P0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
Visually inspect the wiring harness and connectors related to the oxygen sensor circuit for damage, corrosion, chafing or poor contact.
Watch the sensor voltage in live data: a healthy upstream sensor switches rapidly between roughly 0.1 and 0.9 V.
Measure heater resistance on the sensor connector and check the heater fuse and relay.
Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm P2255 does not return.

How to fix P2255

Start with the cheapest and most common causes before replacing expensive parts:

Repair sensor wiring — $80–$250
Replace the oxygen sensor — $150–$450
Fix an exhaust leak near the sensor — $100–$300

How much does it cost to fix P2255?

Repair cost depends on which component actually failed. Typical scenarios for P2255 (parts and labor, USD, independent shop rates):

Repair sensor wiring: $80–$250
Replace the oxygen sensor: $150–$450
Fix an exhaust leak near the sensor: $100–$300

Overall, fixing P2255 usually costs between $80 and $450. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.