P0134
O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 1)
- Severity
- Medium
- Driving
- Drivable — book it in
The module is seeing no activity at all from the upstream oxygen sensor on bank 1 - the signal is flat rather than wrong. Usually this means the circuit is open, the sensor has died completely, or the sensor never reached operating temperature because its heater has failed.
Possible causes
- CommonOpen circuit in the sensor wiring - broken wire or unplugged connector
- CommonFailed oxygen sensor
- CommonFailed sensor heater, so the sensor never warms enough to work
- PossibleBlown fuse on the sensor heater circuit
- PossibleCorroded connector
What you might notice
- Check engine light on
- Worse fuel economy - the module falls back to a default fuel calculation
- Rough running
- Failed emissions test
What to check, in order
- Check the connector is properly seated. A sensor unplugged during other work is a genuinely common cause.
- Check the fuse for the oxygen sensor heater circuit before anything else - it is quick and cheap to eliminate.
- Look for a heater circuit code stored alongside this one. If present, the heater is the cause and the sensor is not warming up.
- Check continuity of the sensor wiring back to the module.
- Replace the sensor once wiring, fuse and connector have been eliminated.
Read this code from your own car
Plug an ELM327 adapter into the OBD-II port under the dashboard. Pin16 reads every stored, pending and permanent code, explains each one like this page does — offline, with no account — and shows what the car recorded when the fault was set.
Where this code sits
P00xxP01xxP02xxP03xxP04xxP05xxP06xxP07xxP08xxP09xxP0AxxP0BxxP0CxxP0DxxP0ExxP0FxxP10xxP11xxP12xxP13xxP14xxP15xxP16xxP17xxP18xxP19xxP1AxxP1BxxP1CxxP1DxxP1ExxP1FxxP20xxP21xxP22xxP23xxP24xxP25xxP26xxP27xxP28xxP29xxP2AxxP2BxxP2CxxP2DxxP2ExxP2FxxP30xxP31xxP32xxP33xxP34xxP35xxP36xxP37xxP38xxP39xxP3AxxP3BxxP3CxxP3DxxP3ExxP3Fxx
Fuel and air metering
P0100P0101P0102P0103P0104P0105P0106P0107P0108P0109P0110P0111P0112P0113P0114P0115P0116P0117P0118P0119P0120P0121P0122P0123P0124P0125P0126P0127P0128P0129P0130P0131P0132P0133P0134P0135P0136P0137P0138P0139P0140P0141P0142P0143P0144P0145P0146P0147P0148P0149P0150P0151P0152P0153P0154P0155P0156P0157P0158P0159P0160P0161P0162P0163P0164P0165P0166P0167P0168P0169P0170P0171P0172P0173P0174P0175P0176P0177P0178P0179P0180P0181P0182P0183P0184P0185P0186P0187P0188P0189P0190P0191P0192P0193P0194P0195P0196P0197P0198P0199