P0134 The upstream oxygen sensor on bank 1 is giving the computer no signal activity

O2 sensor circuit no activity, bank 1 sensor 1

Severity not verified — if the car runs badly, have it inspected

The sources read for this code do not rate its urgency, so no severity is claimed. TroubleCodes.net describes the usual symptom as a check engine light, sometimes with poorer fuel economy or running; have it diagnosed rather than ignoring it.

Source: how we rate severity

P0134 in short

P0134 means the computer detects no activity from the bank 1 sensor 1 oxygen sensor, the one ahead of the catalytic converter. Typical causes are a failed sensor, damaged heater or signal wiring, a blown fuse or low battery voltage. It can cause hesitation and poor fuel economy.

The Delaware DMV list titles P0134 as an O2 sensor circuit with no activity detected on bank 1 sensor 1, and TroubleCodes.net gives the same title. The computer is not seeing the signal change it expects from the upstream sensor.

TroubleCodes.net says a working sensor should reach about 600 degrees C within roughly 60 seconds, and its signal should move outside a baseline of about 390 to 490 millivolts. A sensor that never heats up or never moves sets this code.

Listed causes include damaged heater or signal wiring, blown fuses, a defective sensor, low battery voltage, silicone contamination and, rarely, the computer.

Most likely causes

These are general causes for this code across vehicles. None is specific to one make or model.

  1. Failed oxygen sensor

    Common general cause
    Why it ranks here
    TroubleCodes.net lists a defective sensor among the main causes, and a sensor outside its resistance spec is replaced.
    What would change this
    Rises if resistance is out of specification or the sensor is discoloured or contaminated. Falls if the sensor tests within spec.
    How to test the oxygen (o2) sensor

  2. Damaged heater or signal wiring, or a blown fuse

    Common general cause
    Why it ranks here
    The page lists damaged heater control or signal wiring and blown fuses that stop the sensor element heating.
    What would change this
    Rises if a wire is damaged or open or a fuse is blown. Falls if power, ground and continuity test good.

  3. Low battery or system voltage

    Possible — needs testing
    Why it ranks here
    The page lists low battery voltage as affecting how the heater element warms up.
    What would change this
    Rises if battery or charging voltage is low. Falls if system voltage is normal.

  4. Contaminated sensor from silicone additives or engine fluids in the exhaust

    Possible — needs testing
    Why it ranks here
    The page lists silicone-based additives and oil or coolant entering the combustion chamber as causes.
    What would change this
    Rises if the sensor shows deposits or discolouration, or the engine burns oil or coolant. Falls if the sensor is clean.

What to test first

Start at step 1. Each result tells you what it means and where to go next.

  1. Read all codes and freeze-frame data with a scan tool and write them down before clearing anything.

    Low riskTool: OBD-II scan tool

    • IfHeater or other oxygen sensor codes are stored too

      It meansCheck the shared fuse and wiring first.

      Go to step 2

    • IfOnly P0134 is stored

      It meansInspect wiring and fuses.

      Go to step 2

  2. With the exhaust cold, inspect the sensor wiring and connector for damage, and check the fuses that feed the sensor circuits.

    Use cautionTool: flashlight; fuse tester

    Warning:Exhaust parts and the sensor stay hot long after the engine is off and can cause serious burns. Work only on a cold exhaust and never under a car held up only by a jack.

  3. Test battery voltage, then check the sensor's resistance, power and ground against the maker's specification, and inspect the removed sensor for deposits.

    Use cautionTool: digital multimeter; service information

    Warning:The exhaust and sensor stay hot long after shutdown. Remove the sensor only from a cold exhaust, and follow the specification for your engine rather than guessing at values.

Symptoms

  • Check engine light
  • Hesitation or power loss on acceleration
  • Higher fuel use
  • Black exhaust smoke
  • Hard starting

How to fix

  1. With the exhaust fully cold, inspect the upstream sensor wiring and connector for damage or corrosion.

  2. Check the fuses for the sensor circuits and have the battery voltage tested.

Parts and cost context

  • Oxygen (O2) sensor:Replace the sensor only after wiring, fuses and exhaust leaks are checked. Use the part made for that bank and position. Labour varies; get a quote.

Labor varies by vehicle and shop; get a quote before you approve a repair.

Compare used part prices on PartPriceGuide

On your vehicle

Honda

  • 2007–2008 · CR-V

    Supported by vehicle data

    Honda bulletin SB-08-067 covers the MIL coming on with P0134, P0135, P0171 or P1157. Whether it is still current is not verified.

  • SB-08-067Status unverified

    Honda bulletin: MIL on with P0134, P0135, P0171 or P1157

    2007–2008cr-v · issued · NHTSA 10026826

    Honda bulletin SB-08-067 for the 2007-2008 CR-V. The summary says the MIL comes on with P0134, P0135, P0171 or P1157. Only the NHTSA summary was read, not the full bulletin; the summary does not give the repair.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Subaru

  • 2015 · Impreza

    Supported by vehicle data

    Subaru bulletin 11-144-14 provides reprogramming files for P0420, P2610 and P0134. Whether it is still current is not verified.

  • 11-144-14Status unverified

    Subaru bulletin: reprogramming files for P0420, P2610 and P0134

    2015impreza · issued · NHTSA 10092379

    Subaru bulletin 11-144-14 for the 2015 Impreza. The summary says only that reprogramming files are provided for P0420, P2610 and P0134. Only the NHTSA summary was read, not the full bulletin; the summary does not give the repair.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Nissan

  • 2000–2001 · Sentra

    Supported by vehicle data

    Nissan bulletin NTB02015 covers the warning lamp on with P0134 or P0171 stored. Whether it is still current is not verified.

  • NTB02015Status unverified

    Nissan bulletin: warning lamp on with P0134 or P0171 stored

    2000–2001sentra · issued · NHTSA 629198

    Nissan bulletin NTB02015 for the 2000-2001 Sentra. The summary says the warning lamp is on with P0134 or P0171 stored. Only the NHTSA summary was read, not the full bulletin; the summary does not give the repair.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Chevrolet

  • 2002 · Cavalier

    Supported by vehicle data

    Chevrolet bulletin 3070 covers the Service Engine Soon light with P0130, P0134 and/or P0135. Whether it is still current is not verified.

  • 3070Status unverified

    Chevrolet bulletin: Service Engine Soon light with P0130, P0134 and/or P0135

    2002cavalier · issued · NHTSA 10009605

    Chevrolet bulletin 3070 for the 2002 Cavalier. The summary says the Service Engine Soon light is on with P0130, P0134 and/or P0135. Only the NHTSA summary was read, not the full bulletin; the summary does not give the repair.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • P0135The heater in the upstream oxygen sensor on bank 1 isn't working as the computer expects

    Same system Possible — needs testing

    P0135 is the heater circuit code for the same bank 1 sensor 1; a heater or fuse fault can set either, so check both together.

All Oxygen sensors codes

P0134 questions

Can I keep driving with P0134?

TroubleCodes.net lists power loss, hesitation, extra fuel use and black smoke as possible effects, and the page does not give an urgency rating. Have it diagnosed soon, since a rich mixture can also dilute the oil.

Sources and review

  1. P0134 trouble code page — TroubleCodes.net
  2. SB-08-067: Honda bulletin: MIL on with P0134, P0135, P0171 or P1157 — Honda
  3. 11-144-14: Subaru bulletin: reprogramming files for P0420, P2610 and P0134 — Subaru
  4. NTB02015: Nissan bulletin: warning lamp on with P0134 or P0171 stored — Nissan
  5. 3070: Chevrolet bulletin: Service Engine Soon light with P0130, P0134 and/or P0135 — Chevrolet
  6. On-Board Diagnostic Trouble Codes (generic code title list) — Delaware Division of Motor Vehicles
Last reviewed
Written by
Saurabh K.
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