P1162
HO2S11 Circuit Fault Bank 1 Sensor 1
Causes
- Open or short in HO2S signal or heater wiring
- Faulty HO2S (upstream, bank 1, sensor 1)
- Poor connector pin contact, corrosion, or water intrusion
- Blown fuse, faulty relay, or ECU driver for heater circuit
- Exhaust leaks near the sensor or mechanical damage to sensor
- ECM/PCM internal fault (rare)
Symptoms
- Check Engine Light (MIL) illuminated
- Rough idle or poor drivability when cold
- Increased fuel consumption or richer/leaner running
- Poor emission test results
- Delayed closed-loop operation or limp-home mode in some cars
What to check
- Read freeze frame and live data with a scan tool. Note HO2S11 voltage and heater status.
- Visual inspect sensor, harness and connector for damage, corrosion, or exhaust leaks.
- Check for related codes (heater or other O2 sensor codes) and pending codes.
- With ignition ON (engine OFF) measure heater supply voltage at the sensor connector.
- Measure signal wire voltage with engine warmed; expect switching between ~0.1–0.9 V.
- Measure heater resistance with sensor disconnected (cold) and compare to service spec.
Signal parameters
- Signal voltage (zirconia sensor): ~0.1 V (lean) to ~0.9 V (rich) when warmed and in closed-loop; should show rapid switching at idle (~1 Hz or faster depending on engine).
- Heater supply: ~12 V (or battery voltage) with key ON/engine OFF or switched supply depending on model; control may be via ECU ground driver.
- Heater resistance (typical): low single-digit to low double-digit ohms (commonly ~2–20 Ω) — consult vehicle service data for exact spec.
- Time-to-active: sensor should begin switching shortly after cold start (varies by vehicle, often within a minute).
Diagnostic algorithm
- Verify the code with a scan tool, record freeze frame and any other stored codes.
- Inspect the sensor and harness visually for heat damage, burns, chafing, or corrosion. Repair any obvious damage.
- With the connector disconnected, measure heater resistance across the heater pins. Compare to factory spec. Replace sensor if out of range or open.
- With ignition ON, backprobe the heater power and control/ground circuits at the connector. Confirm battery voltage (or switched battery) is present where expected and the ECM is able to switch the ground when commanded (use scan tool to command heater ON if available).
- With engine at operating temperature, backprobe the signal wire and observe live voltage on a scan tool or DVOM. Look for the expected switching behavior (0.1–0.9 V). If stuck high/low or steady, check wiring to ECM for shorts or opens.
- Perform a continuity and resistance check from sensor connector to ECM connector for both signal and heater circuits (engine OFF, connectors disconnected). Repair any open/shorts and poor grounds.
- Wiggle the harness and connector while monitoring live data to find intermittent faults. Repair or secure harness as needed.
- If wiring and sensor check good but code persists, inspect fuses/relays and test ECM driver outputs. Replace ECM only after confirming sensor and harness are good and following manufacturer diagnostics.
- Clear codes and perform a road test to verify repair. Confirm sensor reaches closed-loop switching and code does not return.
Likely causes
- Damaged wire insulation or chafed harness near exhaust or routing
- Corroded or loose sensor connector
- Failed heater element in the oxygen sensor
- Shorted sensor signal to battery or ground
- Open heater supply or ground due to blown fuse or connector
Fault status
Similar codes
P1162
Fuel Trim Adaptation Additive Per Ignition Bank 1 Low
Causes
- Open or short in HO2S signal or heater wiring
- Faulty HO2S (upstream, bank 1, sensor 1)
- Poor connector pin contact, corrosion, or water intrusion
- Blown fuse, faulty relay, or ECU driver for heater circuit
- Exhaust leaks near the sensor or mechanical damage to sensor
- ECM/PCM internal fault (rare)
Symptoms
- Check Engine Light (MIL) illuminated
- Rough idle or poor drivability when cold
- Increased fuel consumption or richer/leaner running
- Poor emission test results
- Delayed closed-loop operation or limp-home mode in some cars
What to check
- Read freeze frame and live data with a scan tool. Note HO2S11 voltage and heater status.
- Visual inspect sensor, harness and connector for damage, corrosion, or exhaust leaks.
- Check for related codes (heater or other O2 sensor codes) and pending codes.
- With ignition ON (engine OFF) measure heater supply voltage at the sensor connector.
- Measure signal wire voltage with engine warmed; expect switching between ~0.1–0.9 V.
- Measure heater resistance with sensor disconnected (cold) and compare to service spec.
Signal parameters
- Signal voltage (zirconia sensor): ~0.1 V (lean) to ~0.9 V (rich) when warmed and in closed-loop; should show rapid switching at idle (~1 Hz or faster depending on engine).
- Heater supply: ~12 V (or battery voltage) with key ON/engine OFF or switched supply depending on model; control may be via ECU ground driver.
- Heater resistance (typical): low single-digit to low double-digit ohms (commonly ~2–20 Ω) — consult vehicle service data for exact spec.
- Time-to-active: sensor should begin switching shortly after cold start (varies by vehicle, often within a minute).
Diagnostic algorithm
- Verify the code with a scan tool, record freeze frame and any other stored codes.
- Inspect the sensor and harness visually for heat damage, burns, chafing, or corrosion. Repair any obvious damage.
- With the connector disconnected, measure heater resistance across the heater pins. Compare to factory spec. Replace sensor if out of range or open.
- With ignition ON, backprobe the heater power and control/ground circuits at the connector. Confirm battery voltage (or switched battery) is present where expected and the ECM is able to switch the ground when commanded (use scan tool to command heater ON if available).
- With engine at operating temperature, backprobe the signal wire and observe live voltage on a scan tool or DVOM. Look for the expected switching behavior (0.1–0.9 V). If stuck high/low or steady, check wiring to ECM for shorts or opens.
- Perform a continuity and resistance check from sensor connector to ECM connector for both signal and heater circuits (engine OFF, connectors disconnected). Repair any open/shorts and poor grounds.
- Wiggle the harness and connector while monitoring live data to find intermittent faults. Repair or secure harness as needed.
- If wiring and sensor check good but code persists, inspect fuses/relays and test ECM driver outputs. Replace ECM only after confirming sensor and harness are good and following manufacturer diagnostics.
- Clear codes and perform a road test to verify repair. Confirm sensor reaches closed-loop switching and code does not return.
Likely causes
- Damaged wire insulation or chafed harness near exhaust or routing
- Corroded or loose sensor connector
- Failed heater element in the oxygen sensor
- Shorted sensor signal to battery or ground
- Open heater supply or ground due to blown fuse or connector
Fault status
Similar codes
P1162
Exhaust gas recycling coherence
Causes
- Open or short in HO2S signal or heater wiring
- Faulty HO2S (upstream, bank 1, sensor 1)
- Poor connector pin contact, corrosion, or water intrusion
- Blown fuse, faulty relay, or ECU driver for heater circuit
- Exhaust leaks near the sensor or mechanical damage to sensor
- ECM/PCM internal fault (rare)
Symptoms
- Check Engine Light (MIL) illuminated
- Rough idle or poor drivability when cold
- Increased fuel consumption or richer/leaner running
- Poor emission test results
- Delayed closed-loop operation or limp-home mode in some cars
What to check
- Read freeze frame and live data with a scan tool. Note HO2S11 voltage and heater status.
- Visual inspect sensor, harness and connector for damage, corrosion, or exhaust leaks.
- Check for related codes (heater or other O2 sensor codes) and pending codes.
- With ignition ON (engine OFF) measure heater supply voltage at the sensor connector.
- Measure signal wire voltage with engine warmed; expect switching between ~0.1–0.9 V.
- Measure heater resistance with sensor disconnected (cold) and compare to service spec.
Signal parameters
- Signal voltage (zirconia sensor): ~0.1 V (lean) to ~0.9 V (rich) when warmed and in closed-loop; should show rapid switching at idle (~1 Hz or faster depending on engine).
- Heater supply: ~12 V (or battery voltage) with key ON/engine OFF or switched supply depending on model; control may be via ECU ground driver.
- Heater resistance (typical): low single-digit to low double-digit ohms (commonly ~2–20 Ω) — consult vehicle service data for exact spec.
- Time-to-active: sensor should begin switching shortly after cold start (varies by vehicle, often within a minute).
Diagnostic algorithm
- Verify the code with a scan tool, record freeze frame and any other stored codes.
- Inspect the sensor and harness visually for heat damage, burns, chafing, or corrosion. Repair any obvious damage.
- With the connector disconnected, measure heater resistance across the heater pins. Compare to factory spec. Replace sensor if out of range or open.
- With ignition ON, backprobe the heater power and control/ground circuits at the connector. Confirm battery voltage (or switched battery) is present where expected and the ECM is able to switch the ground when commanded (use scan tool to command heater ON if available).
- With engine at operating temperature, backprobe the signal wire and observe live voltage on a scan tool or DVOM. Look for the expected switching behavior (0.1–0.9 V). If stuck high/low or steady, check wiring to ECM for shorts or opens.
- Perform a continuity and resistance check from sensor connector to ECM connector for both signal and heater circuits (engine OFF, connectors disconnected). Repair any open/shorts and poor grounds.
- Wiggle the harness and connector while monitoring live data to find intermittent faults. Repair or secure harness as needed.
- If wiring and sensor check good but code persists, inspect fuses/relays and test ECM driver outputs. Replace ECM only after confirming sensor and harness are good and following manufacturer diagnostics.
- Clear codes and perform a road test to verify repair. Confirm sensor reaches closed-loop switching and code does not return.
Likely causes
- Damaged wire insulation or chafed harness near exhaust or routing
- Corroded or loose sensor connector
- Failed heater element in the oxygen sensor
- Shorted sensor signal to battery or ground
- Open heater supply or ground due to blown fuse or connector
Fault status
Similar codes
P1162
HIGH PRSS PUMP / FUEL LINE MAL
Causes
- Open or short in HO2S signal or heater wiring
- Faulty HO2S (upstream, bank 1, sensor 1)
- Poor connector pin contact, corrosion, or water intrusion
- Blown fuse, faulty relay, or ECU driver for heater circuit
- Exhaust leaks near the sensor or mechanical damage to sensor
- ECM/PCM internal fault (rare)
Symptoms
- Check Engine Light (MIL) illuminated
- Rough idle or poor drivability when cold
- Increased fuel consumption or richer/leaner running
- Poor emission test results
- Delayed closed-loop operation or limp-home mode in some cars
What to check
- Read freeze frame and live data with a scan tool. Note HO2S11 voltage and heater status.
- Visual inspect sensor, harness and connector for damage, corrosion, or exhaust leaks.
- Check for related codes (heater or other O2 sensor codes) and pending codes.
- With ignition ON (engine OFF) measure heater supply voltage at the sensor connector.
- Measure signal wire voltage with engine warmed; expect switching between ~0.1–0.9 V.
- Measure heater resistance with sensor disconnected (cold) and compare to service spec.
Signal parameters
- Signal voltage (zirconia sensor): ~0.1 V (lean) to ~0.9 V (rich) when warmed and in closed-loop; should show rapid switching at idle (~1 Hz or faster depending on engine).
- Heater supply: ~12 V (or battery voltage) with key ON/engine OFF or switched supply depending on model; control may be via ECU ground driver.
- Heater resistance (typical): low single-digit to low double-digit ohms (commonly ~2–20 Ω) — consult vehicle service data for exact spec.
- Time-to-active: sensor should begin switching shortly after cold start (varies by vehicle, often within a minute).
Diagnostic algorithm
- Verify the code with a scan tool, record freeze frame and any other stored codes.
- Inspect the sensor and harness visually for heat damage, burns, chafing, or corrosion. Repair any obvious damage.
- With the connector disconnected, measure heater resistance across the heater pins. Compare to factory spec. Replace sensor if out of range or open.
- With ignition ON, backprobe the heater power and control/ground circuits at the connector. Confirm battery voltage (or switched battery) is present where expected and the ECM is able to switch the ground when commanded (use scan tool to command heater ON if available).
- With engine at operating temperature, backprobe the signal wire and observe live voltage on a scan tool or DVOM. Look for the expected switching behavior (0.1–0.9 V). If stuck high/low or steady, check wiring to ECM for shorts or opens.
- Perform a continuity and resistance check from sensor connector to ECM connector for both signal and heater circuits (engine OFF, connectors disconnected). Repair any open/shorts and poor grounds.
- Wiggle the harness and connector while monitoring live data to find intermittent faults. Repair or secure harness as needed.
- If wiring and sensor check good but code persists, inspect fuses/relays and test ECM driver outputs. Replace ECM only after confirming sensor and harness are good and following manufacturer diagnostics.
- Clear codes and perform a road test to verify repair. Confirm sensor reaches closed-loop switching and code does not return.
Likely causes
- Damaged wire insulation or chafed harness near exhaust or routing
- Corroded or loose sensor connector
- Failed heater element in the oxygen sensor
- Shorted sensor signal to battery or ground
- Open heater supply or ground due to blown fuse or connector
Fault status
Similar codes
P1162
Exhaust gas recycling coherence
Causes
- Open or short in HO2S signal or heater wiring
- Faulty HO2S (upstream, bank 1, sensor 1)
- Poor connector pin contact, corrosion, or water intrusion
- Blown fuse, faulty relay, or ECU driver for heater circuit
- Exhaust leaks near the sensor or mechanical damage to sensor
- ECM/PCM internal fault (rare)
Symptoms
- Check Engine Light (MIL) illuminated
- Rough idle or poor drivability when cold
- Increased fuel consumption or richer/leaner running
- Poor emission test results
- Delayed closed-loop operation or limp-home mode in some cars
What to check
- Read freeze frame and live data with a scan tool. Note HO2S11 voltage and heater status.
- Visual inspect sensor, harness and connector for damage, corrosion, or exhaust leaks.
- Check for related codes (heater or other O2 sensor codes) and pending codes.
- With ignition ON (engine OFF) measure heater supply voltage at the sensor connector.
- Measure signal wire voltage with engine warmed; expect switching between ~0.1–0.9 V.
- Measure heater resistance with sensor disconnected (cold) and compare to service spec.
Signal parameters
- Signal voltage (zirconia sensor): ~0.1 V (lean) to ~0.9 V (rich) when warmed and in closed-loop; should show rapid switching at idle (~1 Hz or faster depending on engine).
- Heater supply: ~12 V (or battery voltage) with key ON/engine OFF or switched supply depending on model; control may be via ECU ground driver.
- Heater resistance (typical): low single-digit to low double-digit ohms (commonly ~2–20 Ω) — consult vehicle service data for exact spec.
- Time-to-active: sensor should begin switching shortly after cold start (varies by vehicle, often within a minute).
Diagnostic algorithm
- Verify the code with a scan tool, record freeze frame and any other stored codes.
- Inspect the sensor and harness visually for heat damage, burns, chafing, or corrosion. Repair any obvious damage.
- With the connector disconnected, measure heater resistance across the heater pins. Compare to factory spec. Replace sensor if out of range or open.
- With ignition ON, backprobe the heater power and control/ground circuits at the connector. Confirm battery voltage (or switched battery) is present where expected and the ECM is able to switch the ground when commanded (use scan tool to command heater ON if available).
- With engine at operating temperature, backprobe the signal wire and observe live voltage on a scan tool or DVOM. Look for the expected switching behavior (0.1–0.9 V). If stuck high/low or steady, check wiring to ECM for shorts or opens.
- Perform a continuity and resistance check from sensor connector to ECM connector for both signal and heater circuits (engine OFF, connectors disconnected). Repair any open/shorts and poor grounds.
- Wiggle the harness and connector while monitoring live data to find intermittent faults. Repair or secure harness as needed.
- If wiring and sensor check good but code persists, inspect fuses/relays and test ECM driver outputs. Replace ECM only after confirming sensor and harness are good and following manufacturer diagnostics.
- Clear codes and perform a road test to verify repair. Confirm sensor reaches closed-loop switching and code does not return.
Likely causes
- Damaged wire insulation or chafed harness near exhaust or routing
- Corroded or loose sensor connector
- Failed heater element in the oxygen sensor
- Shorted sensor signal to battery or ground
- Open heater supply or ground due to blown fuse or connector
Fault status
Similar codes
P1162
HO2S11 Circuit Fault Bank 1 Sensor 1
Causes
- Open or short in HO2S signal or heater wiring
- Faulty HO2S (upstream, bank 1, sensor 1)
- Poor connector pin contact, corrosion, or water intrusion
- Blown fuse, faulty relay, or ECU driver for heater circuit
- Exhaust leaks near the sensor or mechanical damage to sensor
- ECM/PCM internal fault (rare)
Symptoms
- Check Engine Light (MIL) illuminated
- Rough idle or poor drivability when cold
- Increased fuel consumption or richer/leaner running
- Poor emission test results
- Delayed closed-loop operation or limp-home mode in some cars
What to check
- Read freeze frame and live data with a scan tool. Note HO2S11 voltage and heater status.
- Visual inspect sensor, harness and connector for damage, corrosion, or exhaust leaks.
- Check for related codes (heater or other O2 sensor codes) and pending codes.
- With ignition ON (engine OFF) measure heater supply voltage at the sensor connector.
- Measure signal wire voltage with engine warmed; expect switching between ~0.1–0.9 V.
- Measure heater resistance with sensor disconnected (cold) and compare to service spec.
Signal parameters
- Signal voltage (zirconia sensor): ~0.1 V (lean) to ~0.9 V (rich) when warmed and in closed-loop; should show rapid switching at idle (~1 Hz or faster depending on engine).
- Heater supply: ~12 V (or battery voltage) with key ON/engine OFF or switched supply depending on model; control may be via ECU ground driver.
- Heater resistance (typical): low single-digit to low double-digit ohms (commonly ~2–20 Ω) — consult vehicle service data for exact spec.
- Time-to-active: sensor should begin switching shortly after cold start (varies by vehicle, often within a minute).
Diagnostic algorithm
- Verify the code with a scan tool, record freeze frame and any other stored codes.
- Inspect the sensor and harness visually for heat damage, burns, chafing, or corrosion. Repair any obvious damage.
- With the connector disconnected, measure heater resistance across the heater pins. Compare to factory spec. Replace sensor if out of range or open.
- With ignition ON, backprobe the heater power and control/ground circuits at the connector. Confirm battery voltage (or switched battery) is present where expected and the ECM is able to switch the ground when commanded (use scan tool to command heater ON if available).
- With engine at operating temperature, backprobe the signal wire and observe live voltage on a scan tool or DVOM. Look for the expected switching behavior (0.1–0.9 V). If stuck high/low or steady, check wiring to ECM for shorts or opens.
- Perform a continuity and resistance check from sensor connector to ECM connector for both signal and heater circuits (engine OFF, connectors disconnected). Repair any open/shorts and poor grounds.
- Wiggle the harness and connector while monitoring live data to find intermittent faults. Repair or secure harness as needed.
- If wiring and sensor check good but code persists, inspect fuses/relays and test ECM driver outputs. Replace ECM only after confirming sensor and harness are good and following manufacturer diagnostics.
- Clear codes and perform a road test to verify repair. Confirm sensor reaches closed-loop switching and code does not return.
Likely causes
- Damaged wire insulation or chafed harness near exhaust or routing
- Corroded or loose sensor connector
- Failed heater element in the oxygen sensor
- Shorted sensor signal to battery or ground
- Open heater supply or ground due to blown fuse or connector
Fault status
Similar codes
P1162
HO2S11 Circuit Fault Bank 1 Sensor 1
Causes
- Open or short in HO2S signal or heater wiring
- Faulty HO2S (upstream, bank 1, sensor 1)
- Poor connector pin contact, corrosion, or water intrusion
- Blown fuse, faulty relay, or ECU driver for heater circuit
- Exhaust leaks near the sensor or mechanical damage to sensor
- ECM/PCM internal fault (rare)
Symptoms
- Check Engine Light (MIL) illuminated
- Rough idle or poor drivability when cold
- Increased fuel consumption or richer/leaner running
- Poor emission test results
- Delayed closed-loop operation or limp-home mode in some cars
What to check
- Read freeze frame and live data with a scan tool. Note HO2S11 voltage and heater status.
- Visual inspect sensor, harness and connector for damage, corrosion, or exhaust leaks.
- Check for related codes (heater or other O2 sensor codes) and pending codes.
- With ignition ON (engine OFF) measure heater supply voltage at the sensor connector.
- Measure signal wire voltage with engine warmed; expect switching between ~0.1–0.9 V.
- Measure heater resistance with sensor disconnected (cold) and compare to service spec.
Signal parameters
- Signal voltage (zirconia sensor): ~0.1 V (lean) to ~0.9 V (rich) when warmed and in closed-loop; should show rapid switching at idle (~1 Hz or faster depending on engine).
- Heater supply: ~12 V (or battery voltage) with key ON/engine OFF or switched supply depending on model; control may be via ECU ground driver.
- Heater resistance (typical): low single-digit to low double-digit ohms (commonly ~2–20 Ω) — consult vehicle service data for exact spec.
- Time-to-active: sensor should begin switching shortly after cold start (varies by vehicle, often within a minute).
Diagnostic algorithm
- Verify the code with a scan tool, record freeze frame and any other stored codes.
- Inspect the sensor and harness visually for heat damage, burns, chafing, or corrosion. Repair any obvious damage.
- With the connector disconnected, measure heater resistance across the heater pins. Compare to factory spec. Replace sensor if out of range or open.
- With ignition ON, backprobe the heater power and control/ground circuits at the connector. Confirm battery voltage (or switched battery) is present where expected and the ECM is able to switch the ground when commanded (use scan tool to command heater ON if available).
- With engine at operating temperature, backprobe the signal wire and observe live voltage on a scan tool or DVOM. Look for the expected switching behavior (0.1–0.9 V). If stuck high/low or steady, check wiring to ECM for shorts or opens.
- Perform a continuity and resistance check from sensor connector to ECM connector for both signal and heater circuits (engine OFF, connectors disconnected). Repair any open/shorts and poor grounds.
- Wiggle the harness and connector while monitoring live data to find intermittent faults. Repair or secure harness as needed.
- If wiring and sensor check good but code persists, inspect fuses/relays and test ECM driver outputs. Replace ECM only after confirming sensor and harness are good and following manufacturer diagnostics.
- Clear codes and perform a road test to verify repair. Confirm sensor reaches closed-loop switching and code does not return.
Likely causes
- Damaged wire insulation or chafed harness near exhaust or routing
- Corroded or loose sensor connector
- Failed heater element in the oxygen sensor
- Shorted sensor signal to battery or ground
- Open heater supply or ground due to blown fuse or connector
Fault status
Similar codes
P1162
Exhaust gas recycling coherence
Causes
- Open or short in HO2S signal or heater wiring
- Faulty HO2S (upstream, bank 1, sensor 1)
- Poor connector pin contact, corrosion, or water intrusion
- Blown fuse, faulty relay, or ECU driver for heater circuit
- Exhaust leaks near the sensor or mechanical damage to sensor
- ECM/PCM internal fault (rare)
Symptoms
- Check Engine Light (MIL) illuminated
- Rough idle or poor drivability when cold
- Increased fuel consumption or richer/leaner running
- Poor emission test results
- Delayed closed-loop operation or limp-home mode in some cars
What to check
- Read freeze frame and live data with a scan tool. Note HO2S11 voltage and heater status.
- Visual inspect sensor, harness and connector for damage, corrosion, or exhaust leaks.
- Check for related codes (heater or other O2 sensor codes) and pending codes.
- With ignition ON (engine OFF) measure heater supply voltage at the sensor connector.
- Measure signal wire voltage with engine warmed; expect switching between ~0.1–0.9 V.
- Measure heater resistance with sensor disconnected (cold) and compare to service spec.
Signal parameters
- Signal voltage (zirconia sensor): ~0.1 V (lean) to ~0.9 V (rich) when warmed and in closed-loop; should show rapid switching at idle (~1 Hz or faster depending on engine).
- Heater supply: ~12 V (or battery voltage) with key ON/engine OFF or switched supply depending on model; control may be via ECU ground driver.
- Heater resistance (typical): low single-digit to low double-digit ohms (commonly ~2–20 Ω) — consult vehicle service data for exact spec.
- Time-to-active: sensor should begin switching shortly after cold start (varies by vehicle, often within a minute).
Diagnostic algorithm
- Verify the code with a scan tool, record freeze frame and any other stored codes.
- Inspect the sensor and harness visually for heat damage, burns, chafing, or corrosion. Repair any obvious damage.
- With the connector disconnected, measure heater resistance across the heater pins. Compare to factory spec. Replace sensor if out of range or open.
- With ignition ON, backprobe the heater power and control/ground circuits at the connector. Confirm battery voltage (or switched battery) is present where expected and the ECM is able to switch the ground when commanded (use scan tool to command heater ON if available).
- With engine at operating temperature, backprobe the signal wire and observe live voltage on a scan tool or DVOM. Look for the expected switching behavior (0.1–0.9 V). If stuck high/low or steady, check wiring to ECM for shorts or opens.
- Perform a continuity and resistance check from sensor connector to ECM connector for both signal and heater circuits (engine OFF, connectors disconnected). Repair any open/shorts and poor grounds.
- Wiggle the harness and connector while monitoring live data to find intermittent faults. Repair or secure harness as needed.
- If wiring and sensor check good but code persists, inspect fuses/relays and test ECM driver outputs. Replace ECM only after confirming sensor and harness are good and following manufacturer diagnostics.
- Clear codes and perform a road test to verify repair. Confirm sensor reaches closed-loop switching and code does not return.
Likely causes
- Damaged wire insulation or chafed harness near exhaust or routing
- Corroded or loose sensor connector
- Failed heater element in the oxygen sensor
- Shorted sensor signal to battery or ground
- Open heater supply or ground due to blown fuse or connector
Fault status
Similar codes
P1162
Fuel Temperature Sensor Circuit Short To Ground
Causes
- Open or short in HO2S signal or heater wiring
- Faulty HO2S (upstream, bank 1, sensor 1)
- Poor connector pin contact, corrosion, or water intrusion
- Blown fuse, faulty relay, or ECU driver for heater circuit
- Exhaust leaks near the sensor or mechanical damage to sensor
- ECM/PCM internal fault (rare)
Symptoms
- Check Engine Light (MIL) illuminated
- Rough idle or poor drivability when cold
- Increased fuel consumption or richer/leaner running
- Poor emission test results
- Delayed closed-loop operation or limp-home mode in some cars
What to check
- Read freeze frame and live data with a scan tool. Note HO2S11 voltage and heater status.
- Visual inspect sensor, harness and connector for damage, corrosion, or exhaust leaks.
- Check for related codes (heater or other O2 sensor codes) and pending codes.
- With ignition ON (engine OFF) measure heater supply voltage at the sensor connector.
- Measure signal wire voltage with engine warmed; expect switching between ~0.1–0.9 V.
- Measure heater resistance with sensor disconnected (cold) and compare to service spec.
Signal parameters
- Signal voltage (zirconia sensor): ~0.1 V (lean) to ~0.9 V (rich) when warmed and in closed-loop; should show rapid switching at idle (~1 Hz or faster depending on engine).
- Heater supply: ~12 V (or battery voltage) with key ON/engine OFF or switched supply depending on model; control may be via ECU ground driver.
- Heater resistance (typical): low single-digit to low double-digit ohms (commonly ~2–20 Ω) — consult vehicle service data for exact spec.
- Time-to-active: sensor should begin switching shortly after cold start (varies by vehicle, often within a minute).
Diagnostic algorithm
- Verify the code with a scan tool, record freeze frame and any other stored codes.
- Inspect the sensor and harness visually for heat damage, burns, chafing, or corrosion. Repair any obvious damage.
- With the connector disconnected, measure heater resistance across the heater pins. Compare to factory spec. Replace sensor if out of range or open.
- With ignition ON, backprobe the heater power and control/ground circuits at the connector. Confirm battery voltage (or switched battery) is present where expected and the ECM is able to switch the ground when commanded (use scan tool to command heater ON if available).
- With engine at operating temperature, backprobe the signal wire and observe live voltage on a scan tool or DVOM. Look for the expected switching behavior (0.1–0.9 V). If stuck high/low or steady, check wiring to ECM for shorts or opens.
- Perform a continuity and resistance check from sensor connector to ECM connector for both signal and heater circuits (engine OFF, connectors disconnected). Repair any open/shorts and poor grounds.
- Wiggle the harness and connector while monitoring live data to find intermittent faults. Repair or secure harness as needed.
- If wiring and sensor check good but code persists, inspect fuses/relays and test ECM driver outputs. Replace ECM only after confirming sensor and harness are good and following manufacturer diagnostics.
- Clear codes and perform a road test to verify repair. Confirm sensor reaches closed-loop switching and code does not return.
Likely causes
- Damaged wire insulation or chafed harness near exhaust or routing
- Corroded or loose sensor connector
- Failed heater element in the oxygen sensor
- Shorted sensor signal to battery or ground
- Open heater supply or ground due to blown fuse or connector
