P0152 code: O2 Sensor Circuit High Voltage (Bank 2, Sensor 1)
P0152 means o2 Sensor Circuit High Voltage (Bank 2, Sensor 1). The code says where to look, not what failed — the fix depends on which cause your car actually has.
What P0152 means
P0152 means the upstream oxygen sensor on Bank 2 — the fuel-control sensor for the cylinder bank opposite cylinder 1, present only on V-type and flat engines — is sending a signal stuck high, i.e., reporting rich continuously. Two families of cause exist. Electrical: a failing sensor, a contaminated element, or a signal wire shorted to a voltage source. Real: Bank 2 genuinely running rich, from a leaking injector on that bank, excessive fuel pressure, or a fuel-soaked evaporative-purge problem. The distinction is worth a proper look, because a genuinely rich bank wastes fuel, can foul that bank's spark plugs, and can overheat its catalytic converter — problems a new sensor will not touch. As a fuel-control sensor fault, expect some economy loss while the code is active.
P0152 symptoms
- Check-engine light
- Worse fuel economy
- Fuel smell or dark exhaust if the bank is genuinely rich
- Rough idle or fouled plugs on one bank in stronger cases
- Failed emissions test
What it costs to fix P0152
Typical range: $150–$600 · about ~0.3–1.5 hrs of labor
| If the cause is… | Part | Labor |
|---|---|---|
| Upstream oxygen (O2) sensor | $50–$250 | ~0.3–1.5 hrs |
| Wiring / connector repair | $10–$120 | ~0.5–1.5 hrs |
| Exhaust leak repair near the sensor | $20–$200 | ~0.5–2 hrs |
If the sensor is at fault, cost tracks any upstream sensor job, with Bank 2 access on transverse engines the usual labor multiplier. If diagnosis finds a genuinely rich bank — an injector or fuel-pressure issue — the repair belongs to that system and may exceed these figures.
The price swings on which cause it turns out to be — so confirm the cause before paying. Diagnose P0152 for my exact vehicle →
How to fix P0152
Moderate — doable at home with common tools and patience
- Read the voltage and the bank 2 fuel trims together
A conventional zirconia sensor can't generate much more than about 1 volt, so a reading well above that is electrical, not a rich engine. If the signal sits around 0.8–0.9 V and bank 2 long-term trim is pulling fuel hard while bank 1 looks normal, that bank really is rich. Wideband sensors report differently; use the service manual's values for those.
- Unplug the sensor and see whether the high reading follows
With the engine running, disconnect the bank 2 upstream sensor and watch the same PID. A healthy circuit falls to a low or fixed default value once the sensor is out of the picture; if it stays high, the short is in the harness or connector, and a meter on the harness-side signal pin will show voltage that shouldn't be there.
- Look where the signal wire runs beside the heater feed
The sensor's heater gets battery voltage through the same pigtail, so melted or chafed insulation can bridge heater power onto the signal wire. Inspect the loom where it passes the bank 2 manifold heat shield and check the connector for corrosion tracking between terminals; the same heater-to-signal short can also happen inside the sensor body.
- Chase a genuinely rich bank 2
If the trims confirm it, hunt for causes that affect only that bank, such as an injector on the bank 2 side dripping or stuck partly open — black, sooty spark plugs on those cylinders back up the verdict. If both banks run rich, the culprit is shared, like fuel pressure or a purge valve stuck open, and a new sensor won't touch it.
- Read the old sensor's tip before fitting a new one
Once the circuit and mixture check out, replace the sensor and study what came out. A white, chalky, or glossy coating points to coolant or silicone reaching that bank's exhaust — a gasket seeping on that side, or sealant that isn't sensor-safe — and the replacement can be skewed the same way until the source is fixed.
DIY or shop? The trim comparison and the unplug test are quick, decisive home checks that tell you whether to look at wiring, fuel, or the sensor itself. Swapping the sensor is DIY when you can reach it; on engines where the bank 2 upstream sensor hides behind the rear manifold, a lift helps a lot. Hand it over when the evidence says the bank is truly rich — confirming a leaking injector usually means a balance test or pulling the fuel rail — or when the short is buried inside a harness you'd have to unwrap to find.
Tools for the DIY steps: Scan tool with live data and fuel trims · Digital multimeter · Back-probe pins · O2 sensor socket · Spark plug socket · Penetrating oil
Not sure which step applies to your car? Get the likely cause for your exact vehicle before buying anything for P0152.
Start a case with P0152 and your car. Redline weighs these causes against what your car shows, and names the check that would settle it before you buy parts.
Can I drive with P0152?
Redline can’t determine from a symptom or code alone whether your car is safe to drive.
P0152: common questions
What does high voltage from an upstream O2 sensor mean?
The signal is pinned at the rich end. Either Bank 2 really is running rich — leaking injector, high fuel pressure — or the signal is false: a worn/contaminated sensor or a wire shorted to voltage. Fuel-trim data tells the two apart.
Is it safe to drive with P0152?
Not something a code can answer by itself. The cost of waiting is mostly if the bank is genuinely rich — excess fuel can foul plugs and overheat the catalytic converter over time — so aim for diagnosis within days or a few weeks, not months. If you smell fuel or see black smoke, stop driving.
P0152 versus P0172 — what's the difference?
P0152 says the Bank 2 upstream sensor's signal is stuck high; P0172-family codes say the computer concluded a bank is actually running rich. Seeing both together strengthens the case for a real mixture problem rather than a bad sensor.
Why did a new sensor not fix my P0152?
Because the sensor was probably reporting the truth. A genuinely rich Bank 2 — from an injector, fuel-pressure, or purge-valve problem — or a harness shorted to voltage will pin the new sensor's signal exactly like the old one.
Related trouble codes
Don’t have a scanner yet? A ~$25 Bluetooth adapter reads codes like P0152 from your phone. See our guide to the best OBD2 Bluetooth adapters. Run a repair shop? See Redline for shops.
Generic OBD-II reference. Manufacturer-specific behavior varies. Confirm with a scan tool and, for safety-related codes, a professional inspection. Cost ranges are reference ranges, not quotes.
Seeing P0152 on your car?
Every problem becomes a Case. Tell Redline what the car is doing: it shows what the evidence supports, what’s still missing, and what to check next, before you approve a repair.
“Inner pad ~1 mm. Outer pad 3 mm.”
Next: check the slide pins move freely before buying parts.