Jweb2

I have a 2013 GS 350 AWD that I bought in may of this year. The check engine light come on intermittently and then goes off after some freeway driving and a couple on and off cycles. Other than the light being on there the car is running fine. It’s seems like with the cold weather this has been happening more often than not. I swung by one of the auto parts store and had them put it one there scaner.

P0420 which is calatyic system bank one
p1604 startablity malfunction
p1605 rough idling

Any suggestion as to where to start? I have some basic mechanical ability (brakes, rotors, plugs, ext.) and like most of us on here would like to avoid the dealship if possible. Also what scaner would you suggest to aid the diagnosis?

AJLex19

For the first error code P0420, it could be a bad O2 sensor or worst case scenario a bad catalytic - but i'd first start with having someone reputable check that your O2 sensors are working on the drivers side. Catalytics failing seems unlikely unless you are beyond 80k miles (CATS are $$$ so start with your sensors first). Also, sometimes things like cleaning the MAF sensor or possibly replacing exhaust gaskets can resolve the issue. Here's a thread on that error: https://www.clublexus.com/forums/gs-...-bank-2-a.html

P1604 is usually because of a bad battery or bad battery connection - haven't personally encountered P1605 rough idling in my car ownership history so i'm not familiar with that one.

I'd start with having your battery load tested (I think AutoZone does it for free) to see if you're battery is bad. If it is, change it, clear codes using any OBD2 scanner and then see if you get the P0402 problem. Hopefully, it goes away. If not, you should have your O2 sensors looked at/tested.

Do not listen to anyone that tells you to replace your catalytic converter until you have felt like you or your trusted mechanic has exhausted all other possible solutions.

bclexus

P0420 Catalyst System Efficiency Below Threshold (Bank 1):

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 sensor, sends pre-catalyst information to the ECM. The second sensor, the heated oxygen sensor, sends post-catalyst information to the ECM.

In order to detect any deterioration in the three-way catalytic converter, the ECM calculates the oxygen storage capacity of the three-way catalytic converter. This calculation is based on the voltage output of the heated oxygen sensor while performing active air fuel ratio control.

The oxygen storage capacity value is an indication of the oxygen storage capacity of the three-way catalytic converter. 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 the cycle of the waveform for the heated oxygen sensor is long, the oxygen storage capacity is great. There is a direct correlation between the heated oxygen sensor and the oxygen storage capacity of the three-way catalytic converter.

The ECM uses the oxygen storage capacity value to determine the state of the three-way catalytic converter. If any deterioration has occurred, the ECM illuminates the MIL and sets the DTC.
This system determines the deterioration of the entire catalyst system (including the front and rear catalysts), by using the oxygen storage capacity value of the front catalyst, that is more sensitive than the rear catalyst, as the representative value. Therefore, be sure to replace the front and rear catalysts together when catalyst replacement is necessary.

P0420 - OSC value is less than the standard value under active air-fuel ratio control (2 trip detection logic)

Trouble Area:

1. Gas leakage from exhaust system
2. Air fuel ratio sensor (bank 1 sensor 1)
3. Heated oxygen sensor (bank 1 sensor 2)
4. Exhaust manifold sub-assembly RH (TWC: Front catalyst) and front exhaust pipe assembly (TWC: Rear catalyst)

Much more - too much to post

bclexus

P1604 Startability Malfunction

This DTC is stored when the engine does not start even though the STA signal is input or when the engine takes a long time to start, and when the engine speed is low or the engine stalls just after the engine starts.
Using the GTS, the conditions present when the DTC was stored can be confirmed by referring to the freeze frame data. Freeze frame data records engine conditions when a malfunction occurs. This information can be useful when troubleshooting.

It is necessary to check if the vehicle ran out of fuel before performing troubleshooting, as this DTC is also stored when there is engine starting trouble due to running out of fuel.

DTC Detection Condition (Either condition is met):

1. The engine speed is less than 500 rpm with the STA signal on for a certain amount of time (refer to the illustration below) (1 trip detection logic).
2. After the engine starts (engine speed is 500 rpm or more), the engine speed drops to 200 rpm or less within approximately 2 seconds (1 trip detection logic).

Trouble Area:

1. Immobiliser system
2. Engine assembly (excess friction, compression loss)
3. Starter assembly
4. Crankshaft position sensor
5. VVT sensor
6. Engine coolant temperature sensor
7. Fuel pump
8. Fuel pump control circuit
9. Fuel pipes
10. Fuel injector assembly
11. Throttle body with motor assembly
12. Pressure regulator
13. Battery
14. Drive plate
15. Spark plug
16. Ignition coil circuit
17. Intake system
18. Camshaft timing oil control valve assembly
19. Mass air flow meter
20. Air fuel ratio sensor
21. Valve timing
22. Fuel
23. Purge VSV
24. Intake valve
25. Exhaust valve
26. ECM

Much more - too much to post

bclexus

P1605 Rough Idling

This DTC is stored if the engine speed drops below the set speed.

Using the GTS, the conditions present when the DTC was stored can be confirmed by referring to the freeze frame data. Freeze frame data records engine conditions when a malfunction occurs. This information can be useful when troubleshooting.

It is necessary to check if the vehicle ran out of fuel before performing troubleshooting, as this DTC is also stored when idling is unstable due to running out of fuel.

DTC Detection Condition: After 5 seconds or more elapse after starting the engine, with the engine running, the engine speed drops to 400 rpm or less (1 trip detection logic).

Trouble Area:

1. Air leak in intake system
2. Purge VSV
3. Brake booster
4. Mass air flow meter
5. Engine coolant temperature sensor
6. Water inlet with thermostat sub-assembly
7. Power supply circuit (purge VSV, air fuel ratio sensor, fuel injector assembly, ignition coil assembly)
8. Fuel pump
9. Fuel pump control circuit
10. Fuel line
11. PCV valve and hose
12. Camshaft timing oil control valve
13. Knock sensor
14. Ignition system
15. Air conditioning system
16. Power steering system
17. Electrical load signal system
18. Charging system
19. A/T system
20. Park/neutral position switch assembly
21. ECM
22. Wire harness or connector
23. Immobiliser system

Much more - too much to post

bclexus

With the possible 'trouble areas' I posted (in the above 3 posts) for the three trouble codes you provided it would be best to visit your local Lexus dealer to have them troubleshoot your car's problem. The diagnosis and troubleshooting procedure for all three of those trouble codes are extremely lengthy...and it is highly doubtful anyone would be able to complete the troubleshooting procedures without the necessary equipment and extensive training. That said, you may get lucky and find a disconnected hose or something similar, but you'd need to have a four-leaf clover, a rabbit's foot and a chock of red air from a Irish baby in your pocket to be that lucky...

ItzFilyO

Make sure it's not just a loose gas cap.

mmm def

Probably an O2 sensor

Byprodrive

iTrader: (1)

Different code for that.