Is mechanic right? CEL - P0430

He said it was O2 sensor but didn't know which on since it just said "430" as he said. I did a little searching and am guessing that's p0430.

He took out the lower sensor since it was an easy thing to do and said he was going to check for swelling. He said it looked fine and was probably the upper.

No idea if he reset the light but it's off now....

Truck does idle rough... light goes on and off but has been staying on longer now. To me it does act like an 02 sensor issue. Just want to make sure his educated guess to being the top one sounds correct? Truck has over 130k on it.

BTW this is our county garage mechanic. He works on fords and chevys all day.. Does a lot of side jobs but have heard he can be shady at times.

 

Kinda sketchy

 

if you have an autozone in your area next time the light is on take it to them they can read the code for free. other part stores may have this ability but i dont know.

 

yep advance and i am sure o'reillys does too

 

I think they suggest you replace them at 100k regardless

 

Swelling lol all I have to say wtf. You can't check a o2 sensor like that. That code is for bank 2 cat which is the driverside. I'm a Toyota tech. In a rare case the lower a/f sensor would set a cat code so u could try that first since it is cheaper. Let me know how it goes

 

Auto zone's sucks.. it gives you general area.. I did go there first and they said exhaust/air...

I still have to ask him if he reset my light.. it's still off after the "cleaned" the bottom sensor.. it may be that one if he didn't reset the light. It's been running smooth again.

 

I'm no pro at this but here's my two cents. That's the code for "catalytic converter inefficiency". The PCM compares the 02 content of the exhaust before and after the converter. The upstream sensor is also used to adjust the fuel mixture. Even if the upstream sensor was bad and the PCM was setting the mixture wrong, there still should be a difference in readings between the two sensors. Most likely, the Cat itself is bad. The way to check it would be with an exhaust gas analyzer like what's used to smog check an engine. Pull both 02 sensors and "sniff" the holes where the sensors install.

The way I see it, if you're gonna blame the sensor, you should do that only after you confirm the cat is doing what it's supposed to do.

My sister just had this happen on her CRV. Same fault code. Her mechanic changed the cat and the problem went away.

 

I would say run rough yes. A clogged cat will make it run very rough an sometimes won't run at all trust me I've seen it a few times.

 

Yea it was just at idle it would run a bit rough...

but it's fine now?

 

Ok , the following post contains the FACTORY mechanics service manual on this code. I fixed mine with 02 sensors from Amazon. make sure they are denso. sorry its long

1GR-FE ENGINE CONTROL SYSTEM ​

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– SFI SYSTEM ES–209​

ES​

MONITOR DESCRIPTION​

The ECM uses sensors mounted in front of and behind the Three-Way Catalytic Converter (TWC) to
monitor its efficiency.
The first sensor, the Air-Fuel Ratio (A/F) sensor, sends pre-catalyst information to the ECM. The second
sensor, the Heated Oxygen (HO2) sensor, sends post-catalyst information to the ECM.
In order to detect any deterioration in the TWC, the ECM calculates the Oxygen Storage Capacity (OSC)
of the TWC. This calculation is based on the voltage output of the HO2 sensor while performing active airfuel
ratio control, rather than the conventional detecting method, which uses the locus ratio.
The OSC value is an indication of the oxygen storage capacity of the TWC. When the vehicle is being
driven with a warm engine, active air-fuel ratio control is performed for approximately 15 to 20 seconds.
When it is performed, the ECM deliberately sets the air-fuel ratio to lean or rich levels. If a rich-lean cycle
of the HO2 sensor is long, the OSC becomes greater. There is a direct correlation between the OSCs of
the HO2 sensor and the TWC.
The ECM uses the OSC value to determine the state of the TWC. If any deterioration has occurred, it
illuminates the MIL and sets a DTC.
HINT:
• Bank 1 refers to the bank that includes cylinder No. 1.
• Bank 2 refers to the bank that does not include cylinder No. 1.
• Sensor 1 refers to the sensor closest to the engine assembly.
• Sensor 2 refers to the sensor farthest away from the engine assembly.​

MONITOR STRATEGY​

DTC P0420 Catalyst System Efficiency Below Threshold
(Bank 1)
DTC P0430 Catalyst System Efficiency Below Threshold
(Bank 2)​

DTC No. DTC Detection Conditions Trouble Areas​

P0420 OSC value smaller than standard value under active air-fuel
ratio control (2 trip detection logic)
• Gas leakage from exhaust system
• A/F sensor (bank 1 sensor 1)
• HO2 sensor (bank 1 sensor 2)
• Exhaust manifold (TWC)
P0430 OSC value smaller than standard value under active air-fuel
ratio control (2 trip detection logic)
• Gas leakage from exhaust system
• A/F sensor (bank 2 sensor 1)
• HO2 sensor (bank 2 sensor 2)
• Exhaust manifold (TWC)
Related DTCs P0420: Catalyst Deterioration
P0430: Catalyst Deterioration
Required Sensors/Components (Main) A/F sensor and heated oxygen sensor
Required Sensors/Components (Related) Intake air temperature sensor, mass air flow meter, crankshaft position sensor and
engine coolant temperature sensor
Frequency of Operation Once per driving cycle
Duration 30 seconds or more
MIL Operation 2 driving cycles
Sequence of Operation None​

ES–210 ​

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1GR-FE ENGINE CONTROL SYSTEM ​

– SFI SYSTEM​

ES​

TYPICAL ENABLING CONDITIONS
TYPICAL MALFUNCTION THRESHOLDS
MONITOR RESULT​

Detailed information on Checking Monitor Status (See page ​

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ES-19).​

CONDITIONING FOR SENSOR TESTING​

HINT:
Perform the operation with the engine speeds and time durations described below prior to checking the
waveforms of the A/F and HO2 sensors. This is in order to activate the sensors sufficiently to obtain the
appropriate inspection results.​

Monitor runs whenever following DTCs not present
P0011 (VVT System 1 - Advance)
P0012 (VVT System 1 - Retard)
P0021 (VVT System 2 - Advance)
P0022 (VVT System 2 - Retard)
P0031, P0032, P0051, P0052 (A/F sensor heater - Sensor 1)
P0037, P0038, P0057, P0058 (HO2 sensor Heater - Sensor 2)
P0100 - P0103 (MAF meter)
P0115 - P0118 (ECT sensor)
P0120 - P0223, P2135 (TP sensor)
P0125 (Insufficient ECT for closed loop)
P0136, P0156 (HO2 Sensor - Sensor 2)
P0171, P0172 (Fuel system)
P0300 - P0306 (Misfire)
P0335 (CKP sensor)
P0340 (CMP sensor)
P0351 - P0356 (Ignitor)
P0500 (VSS)
P2196, P2198 (A/F sensor - rationality)
P2A00, P2A03 (A/F sensor - slow response)
Battery voltage 11 V or more
IAT -10​

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°C (14°F) or more
Engine coolant temperature sensor 75°C (167°F) or more
Atmospheric pressure coefficient 0.75 or more
Delay time after IDCE ON Less than 5 seconds
Engine RPM Less than 3,200 rpm
A/F sensor status Activated
Fuel system status Closed loop
Delay time after fuel cut 10 seconds or more
Engine load 10 to 70 %
All of the following conditions are met Condition 1, 2 and 3
1. Mass air flow rate 5 to 70 g/sec
2. Front catalyst temperature (estimated) 650 to 840°C (1,202 to 1,544°F)
3. Rear catalyst temperature (estimated) 100 to 900°C (212 to 1,652°F)
Oxygen Storage Capacity (OSC) of Three-Way Catalytic Converter (TWC) Less than 0.04 g​

1GR-FE ENGINE CONTROL SYSTEM ​

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– SFI SYSTEM ES–211​

ES​

(a) Connect an intelligent tester to the DLC3.
(b) Start the engine and warm it up with all the accessories switched OFF, until the engine coolant
temperature stabilizes.
(c) Run the engine at an engine speed of between 2,500 rpm and 3,000 rpm for at least 3 minutes.
(d) While running the engine at 3,000 rpm for 2 seconds and 2,000 rpm for 2 seconds, check the
waveforms of the A/F and HO2 sensors using the tester.
HINT:
• If either of the voltage outputs of the Air-Fuel Ratio (A/F) or Heated Oxygen (HO2) sensor does not
fluctuate, or either of the sensors makes a noise, the sensor may be malfunctioning.
• If the voltage outputs of both the sensors remain lean or rich, the air-fuel ratio may be extremely lean or
rich. In such cases, perform the following A/F CONTROL using an intelligent tester.
• If the Three-Way Catalytic Converter (TWC) has deteriorated, the HO2 sensor (located behind the
TWC) voltage output fluctuates up and down frequently, even under normal driving conditions (active
air-fuel ratio control is not performed).​

(c)
Engine Speed
3,000 rpm
2,000 rpm
Idling
Ignition Switch OFF
(a)
(b)
(d)
(d)
Warming up At least 3 minutes
2 seconds
Check
Time​

A118003E01​

ES–212 ​

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1GR-FE ENGINE CONTROL SYSTEM ​

– SFI SYSTEM​

ES​

CONDITIONING FOR SENSOR TESTING​

HINT:
Intelligent tester only:
Malfunctioning areas can be identified by performing the A/F CONTROL function provided in the ACTIVE
TEST. The A/F CONTROL function can help to determine whether the Air-Fuel Ratio (A/F) sensor, Heated
Oxygen (HO2) sensor and other potential trouble areas are malfunctioning.
The following instructions describe how to conduct the A/F CONTROL operation using an intelligent
tester.
(1) Connect an intelligent tester to the DLC3.
(2) Start the engine and turn the tester ON.
(3) Warm up the engine at an engine speed of 2,500 rpm for approximately 90 seconds.
(4) Select the following menu items: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL.
(5) Perform the A/F CONTROL operation with the engine in an idling condition (press the RIGHT or LEFT
button to change the fuel injection volume).
(6) Monitor the voltage outputs of the A/F and HO2 sensors (AFS B1S1 and O2S B1S2 or AFS B2S1 and
O2S B2S2) displayed on the tester.
HINT:
• The A/F CONTROL operation lowers the fuel injection volume by 12.5 % or increases the injection
volume by 25 %.
• Each sensor reacts in accordance with increases and decreases in the fuel injection volume.​

Standard​

Tester Display
(Sensor) Injection Volumes Status Voltages
AFS B1S1 or AFS B2S1
(A/F) +25 % Rich Less than 3.0
AFS B1S1 or AFS B2S1
(A/F) -12.5 % Lean More than 3.35
O2S B1S2 or O2S B2S2
(HO2) +25 % Rich More than 0.55
O2S B1S2 or O2S B2S2
(HO2) -12.5 % Lean Less than 0.4​

Voltage output when active air-fuel ratio control not performed
Normal Catalyst Deteriorated Catalyst
Waveform of
HO2 Sensor
behind TWC
Waveform of
A/F Sensor in
front of TWC
3.5 V
3.0 V
1.0 V
0 V
10 seconds 10 seconds​

A121610E01​

1GR-FE ENGINE CONTROL SYSTEM ​

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– SFI SYSTEM ES–213​

ES​

NOTICE:
The Air-Fuel Ratio (A/F) sensor has an output delay of a few seconds and the Heated Oxygen
(HO2) sensor has a maximum output delay of approximately 20 seconds.​

• Following the A/F CONTROL procedure enables technicians to check and graph the voltage outputs of
both the A/F and HO2 sensors.
• To display the graph, select the following menu items on the tester: DIAGNOSIS / ENHANCED OBD II
/ ACTIVE TEST / A/F CONTROL / USER DATA / AFS B1S1 and O2S B1S2 or AFS B2S1 and O2S
B2S2, and press the YES button and then the ENTER button followed by the F4 button.
HINT:
Read freeze frame data using an intelligent tester. Freeze frame data record the engine condition when
malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was
moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other
data, from the time the malfunction occurred.
(a) Connect an intelligent tester to the DLC3.
(b) Turn the ignition switch ON and turn the tester ON.
(c) Select the following menu items: DIAGNOSIS /
ENHANCED OBD II / DTC INFO / CURRENT CODES.
(d) Read DTCs.​

Result​

Case A/F Sensor (Sensor 1)
Output Voltage
HO2 Sensor (Sensor 2)
Output Voltage
Main Suspected
Trouble Areas​

1
Injection volume
+25 %
-12.5 %
Injection volume
+25 %
-12.5 %
-
Output voltage
More than 3.35 V
Less than 3.0 V
Output voltage
More than 0.55 V
Less than 0.4 V
2
Injection volume
+25 %
-12.5 %
Injection volume
+25 %
-12.5 % • A/F sensor
• A/F sensor heater
Output voltage • A/F sensor circuit
Almost
no reaction
Output voltage
More than 0.55 V
Less than 0.4 V
3
Injection volume
+25 %
-12.5 %
Injection volume
+25 %
-12.5 % • HO2 sensor
• HO2 sensor heater
Output voltage • HO2 sensor circuit
More than 3.35 V
Less than 3.0 V
Output voltage
Almost
no reaction
4
Injection volume
+25 %
-12.5 %
Injection volume
+25 %
-12.5 %
• Injector
• Fuel pressure
• Gas leakage from
exhaust system
(Air-fuel ratio extremely
lean or rich)
Output voltage
Almost
no reaction
Output voltage
Almost
no reaction​

1 ​

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CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0420 AND/OR P0430)​

Display (DTC Output) Proceed To
P0420 and/or P0430 A​

ES–214 ​

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1GR-FE ENGINE CONTROL SYSTEM ​

– SFI SYSTEM​

ES​

HINT:
If any DTCs other than P0420 or P0430 are output,
troubleshoot those DTCs first.​

B
A​

(a) Connect an intelligent tester to the DLC3.
(b) Start the engine and turn the tester ON.
(c) Warm up the engine at an engine speed of 2,500 rpm for
approximately 90 seconds.
(d) Select the following menu items: DIAGNOSIS /
ENHANCED OBD II / ACTIVE TEST / A/F CONTROL.
(e) Perform the A/F CONTROL operation with the engine in
an idling condition (press the RIGHT or LEFT button to
change the fuel injection volume).
(f) Monitor the voltage outputs of the A/F and HO2 sensors
(AFS B1S1 and O2S B1S2 or AFS B2S1 and O2S
B2S2) displayed on the tester.
HINT:
• The A/F CONTROL operation lowers the fuel injection
volume by 12.5 % or increases the injection volume
by 25 %.
• Each sensor reacts in accordance with increases and
decreases in the fuel injection volume.​

Standard
Result​

P0420 and/or P0430 and other DTCs B
Display (DTC Output) Proceed To​

GO TO DTC CHART​

2 ​

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PERFORM ACTIVE TEST USING INTELLIGENT TESTER (A/F CONTROL)​

Tester Display
(Sensor) Injection Volumes Status Voltages
AFS B1S1 or AFS B2S1
(A/F) +25 % Rich Less than 3.0
AFS B1S1 or AFS B2S1
(A/F) -12.5 % Lean More than 3.35
O2S B1S2 or O2S B2S2
(HO2) +25 % Rich More than 0.55
O2S B1S2 or O2S B2S2
(HO2) -12.5 % Lean Less than 0.4
Status
AFS B1S1
or
AFS B2S1
Status
O2S B1S2
or
O2S B2S2
A/F Condition and A/F and
HO2 Sensors Conditions Misfires Main Suspected Trouble Areas Proceed
To
Lean/Rich Lean/Rich Normal - • Three-Way Catalytic Converter (TWC)
• Gas leakage from exhaust system A
Lean Lean/Rich A/F sensor malfunction - • A/F sensor
B
Rich Lean/Rich A/F sensor malfunction - • A/F sensor
Lean/Rich Lean HO2 sensor malfunction - • HO2 sensor
• Gas leakage from exhaust system
C
Lean/Rich Rich HO2 sensor malfunction - • HO2 sensor
• Gas leakage from exhaust system​

1GR-FE ENGINE CONTROL SYSTEM ​

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– SFI SYSTEM ES–215​

ES​

Lean: During A/F CONTROL, the A/F sensor output
voltage (AFS) is consistently more than 3.35 V, and
the HO2 sensor output voltage (O2S) is consistently
less than 0.4 V.
Rich: During A/F CONTROL, the AFS is consistently
less than 3.0 V, and the O2S is consistently more than
0.55 V.
Lean/Rich: During A/F CONTROL of the ACTIVE
TEST, the output voltage of the HO2 sensor
alternates correctly.​

B
C
A
OK:
No gas leakage.
NG
OK​

Lean Lean Actual air-fuel ratio lean May occur
• Extremely rich or lean actual air-fuel
ratio
• Gas leakage from exhaust system
A
Rich Rich Actual air-fuel ratio rich -
• Extremely rich or lean actual air-fuel
ratio
• Gas leakage from exhaust system
Status
AFS B1S1
or
AFS B2S1
Status
O2S B1S2
or
O2S B2S2
A/F Condition and A/F and
HO2 Sensors Conditions Misfires Main Suspected Trouble Areas Proceed
To​

CHECK AND REPLACE AIR FUEL RATIO
SENSOR
CHECK AND REPLACE HEATED OXYGEN
SENSOR, AND CHECK AND REPAIR
EXHAUST GAS LEAKAGE​

3 ​

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CHECK FOR EXHAUST GAS LEAKAGE
REPAIR OR REPLACE EXHAUST GAS
LEAKAGE POINT​

REPLACE THREE-WAY CATALYTIC CONVERTER

 

print that out and take it to him

 

Y'all are over complicating things. It's a cat code. If it becomes clogged it will run rough and if u replace the cat it's a good idea to do the sensors at the same time because they have been getting bad readings for a while. An you have to remove them anyway to do the cat