What Does P1152 Mean?
This code indicates the upstream heated oxygen sensor on Bank 2 is stuck indicating a persistent rich condition, failing to switch between lean and rich as expected. The ECM has detected that the Bank 2 Sensor 1 voltage remains above 0.45V for an extended period. This is the Bank 2 equivalent of P1132 and indicates excess fuel delivery to Bank 2 cylinders or a sensor fault providing false rich readings.
Common Causes
30%
Leaking or stuck-open fuel injector(s) on Bank 2
25%
Faulty Bank 2 upstream O2 sensor biased rich or contaminated
18%
Excessive fuel pressure from a failed fuel pressure regulator
15%
EVAP purge valve stuck open flooding the intake with fuel vapors
12%
Coolant leaking into Bank 2 combustion chambers (head gasket, intake manifold gasket) causing false rich readings
Diagnostic Steps
1
Monitor Bank 2 short-term and long-term fuel trim values; high negative values confirm the ECM is attempting to lean out a rich condition.
2
Watch the Bank 2 Sensor 1 O2 voltage waveform; a sensor stuck above 0.6-0.7V indicates a rich condition or sensor fault.
3
Compare Bank 1 and Bank 2 fuel trims to determine if the rich condition is isolated to Bank 2 or system-wide.
4
Check fuel pressure with a gauge and verify the fuel pressure regulator responds correctly to manifold vacuum changes.
5
Perform a cylinder balance test to identify any leaking injectors on Bank 2.
6
Inspect Bank 2 spark plugs for heavy carbon (soot) deposits or wet fouling indicating rich combustion or coolant intrusion.
Estimated Repair Cost
$100 - $550
Parts + labor, varies by vehicle and location
This code indicates the upstream heated oxygen sensor on Bank 2 is stuck indicating a persistent rich condition, failing to switch between lean and rich as expected. The ECM has detected that the Bank 2 Sensor 1 voltage remains above 0.45V for an extended period. This is the Bank 2 equivalent of P11...
The most common cause of P1152 (Lack of Upstream Heated Oxygen Sensor Switch - Sensor Indicates Rich - Bank No. 2) is: Leaking or stuck-open fuel injector(s) on Bank 2
Typical repair costs for P1152 range from $100 to $550, depending on the vehicle, location, and whether you do it yourself or go to a shop.
A persistent rich condition on Bank 2 dilutes engine oil with fuel, accelerating wear. Excess unburned fuel can overheat the Bank 2 catalytic converter, potentially creating a fire risk in extreme cases. Fuel economy will also be noticeably reduced.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1152 to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel System / Emissions
Difficulty
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