P2243
O2 Sensor Reference Voltage Circuit/Open (Bank 1 Sensor 1)
- Severity
- Medium
- Driving
- Drivable — book it in
An open circuit or general fault in the reference voltage circuit for the upstream oxygen sensor on bank 1. A wideband oxygen sensor is not a simple voltage generator like the older narrowband type - the module supplies it with a reference and measures the current needed to hold the sensor at a fixed point. Lose that reference and the sensor cannot report at all, so the module falls back to a fixed fuelling table.
Possible causes
- CommonWiring or connector fault on the reference circuit
- CommonCorroded connector at the sensor - it sits in the exhaust heat
- CommonFailed oxygen sensor loading the reference circuit
- PossibleChafed harness against the exhaust
- PossibleFailed control module reference supply
What you might notice
- Check engine light on
- Worse fuel economy
- Failed emissions test
- Rough running in some conditions
- Often little that the driver notices
What to check, in order
- Inspect the connector at the sensor first. It lives in the hottest, dirtiest part of the exhaust and its connector suffers accordingly.
- Check the harness where it passes near the exhaust for heat and chafe damage - this is the most common wiring failure on an oxygen sensor circuit.
- Unplug the sensor and see whether the reference recovers. If it does, the sensor is loading the circuit.
- Check whether both banks have faulted. Both at once points at a shared reference or earth rather than at two failed sensors.
- Do not fit a new sensor before the wiring is cleared. Wideband sensors are expensive and their circuits fail more often than they do.
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 - injector circuits
P2200P2201P2202P2203P2204P2205P2206P2207P2208P2209P2210P2211P2212P2213P2214P2215P2216P2217P2218P2219P2220P2221P2222P2223P2224P2225P2226P2227P2228P2229P2230P2231P2232P2233P2234P2235P2236P2237P2238P2239P2240P2241P2242P2243P2244P2245P2246P2247P2248P2249P2250P2251P2252P2253P2254P2255P2256P2257P2258P2259P2260P2261P2262P2263P2264P2265P2266P2267P2268P2269P2270P2271P2272P2273P2274P2275P2276P2277P2278P2279P2280P2281P2282P2283P2284P2285P2286P2287P2288P2289P2290P2291P2292P2293P2294P2295P2296P2297P2298P2299