P1129 on Honda
Closed Loop Fueling Not Achieved - Bank 2
P1129 on Honda vehicles indicates closed loop fueling not achieved - bank 2. Au7o has documented this code across 1 Honda model — most commonly on Civic. Bank 2 version of P1128: the PCM was unable to establish closed-loop fuel control on the second bank within the expected time, leaving fueling on the open-loop table with degraded economy and emissions. Typical repair costs on Honda range from $40 to $180, depending on the specific model and root cause.
Common Causes of P1129
- •Stuck-open thermostat / engine never reaching operating temperature
- •Bank 2 upstream oxygen sensor or its heater circuit failed
- •Exhaust leak ahead of the bank 2 sensor
- •Failed engine coolant temperature sensor
- •Wiring or connector corrosion at the bank 2 sensor
P1129 on Honda by Model
Honda Civic(1 issue)
- MAP Sensor Failure (1.6L D-Series)1996-1999
The manifold absolute pressure (MAP) sensor mounted on the throttle body of 1.6L D16 Civics commonly fails as it ages, losing the ability to hold vacuum or drifting out of its 0.5-4.5V calibration range. Because the PCM uses MAP voltage as the primary load input on these speed-density systems, a failing sensor causes the ECU to mis-fuel and mis-time the engine. Failures often set P0107 / P0108 / P1128 / P1129 codes and frequently coincide with cracked vacuum hoses on the upper intake.
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View P1129 across all makes →Frequently Asked Questions
What does P1129 mean on Honda?▼
P1129 stands for "Closed Loop Fueling Not Achieved - Bank 2." Bank 2 version of P1128: the PCM was unable to establish closed-loop fuel control on the second bank within the expected time, leaving fueling on the open-loop table with degraded economy and emissions. On Honda specifically, this code is documented across 1 model.
What causes P1129 on Honda vehicles?▼
Common causes on Honda: Stuck-open thermostat / engine never reaching operating temperature, Bank 2 upstream oxygen sensor or its heater circuit failed, Exhaust leak ahead of the bank 2 sensor, Failed engine coolant temperature sensor, Wiring or connector corrosion at the bank 2 sensor. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P1129 on a Honda?▼
Repair costs on Honda range from $40 to $180, depending on the specific model and root cause.
Which Honda models have P1129 documented?▼
Au7o has documented P1129 on 1 Honda model: Civic.