Heated Oxygen Sensors (Ho2S) - Upstream

DTC P0133, P0153 DETECTION CONDITION & POSSIBLE CAUSES

DTC P0133, P0153	HEATED OXYGEN SENSORS (HO2S) UPSTREAM
DETECTION CONDITION	P0133 indicates the frequency and amplitude response rate of HO2S-11 (front RH) is below calibrated limit. P0153 indicates the frequency and amplitude response rate of HO2S-21 (front LH) is below calibrated limit.
POSSIBLE CAUSE	Contaminated HO2S Exhaust leaks Shorted or open wires Improper fueling Mass air flow (MAF) sensor Deteriorating HO2S Inlet air leaks
HINT	HO2S Description Detects the presence of oxygen in the exhaust and produces a variable voltage (0.0-1.1 V) according to the amount of oxygen detected. A high concentration of oxygen (lean air/fuel ratio) in the exhaust produces a low voltage signal (less than 0.4 V) A low concentration of oxygen (rich air/fuel ratio) in the exhaust produces a high voltage signal (greater than 0.6 V) Provides feedback to the powertrain control module (PCM) indicating air/fuel ratio in order to achieve a near stoichiometric air/fuel ratio of 14.7:1 during closed loop engine operation.
Courtesy of MAZDA MOTORS CORP.
Courtesy of MAZDA MOTORS CORP.
Courtesy of MAZDA MOTORS CORP.

DTC P0133, P0153 DIAGNOSTIC PROCEDURE

DTC P0133, P0153		HEATED OXYGEN SENSORS (HO2S) UPSTREAM
STEP	INSPECTION		ACTION
1	Was the PCM quick test performed?	Yes	Go to next step.
1	Was the PCM quick test performed?	No	Perform PCM quick test. See PCM QUICK TEST .
2	CHECK FOR SOURCE OF POTENTIAL HO2S CONTAMINATION Investigate the following items as potential sources of HO2S contamination: Use of unapproved silicone sealers Fuel contaminated with silicone additives Excessive oil burning (i.e., rings, valve seals and/or oil overfill) Engine coolant leaking internally in the engine Lead contaminated fuel Short drive cycles in cold weather Use of unapproved cleaning agents Are any of the above conditions present?	Yes	Repair source of contamination. Replace HO2S and oil/filter. See HEATED OXYGEN SENSOR (HO2S) REMOVAL / INSTALLATION . Go to step 8.
2		No	Go to next step.
3	CHECK FOR UNMETERED AIR LEAKS Fuel calculations can be affected by unmetered air leaks. Carefully inspect the following areas for potential air leaks: Hoses connecting MAF sensor assembly Hoses connecting to throttle body Intake manifold gasket leaks PCV disconnected Vacuum lines disconnected Improperly seated dipstick tube and oil filler cap Exhaust leaks at flanges and gaskets Are there any air leaks?	Yes	Repair source of air leak. Go to step 8.
3		No	Go to next step.
4	CHECK HO2S CIRCUIT WIRING WITH PCM CONNECTED Disconnect suspect HO2S. Jumper HO2S SIG to VPWR at the HO2S harness connector. Key ON, Engine OFF (KOEO). Access O2S11 for P0133 or O2S21 for P0153 and note the voltage. Is the voltage greater than 1.50 volt?	Yes	Go to next step.
4		No	Remove jumper. Go to step 6.
5	CHECK FOR SHORT TO VPWR AND VREF. Disconnect WDS or equivalent tester. KOEO. Measure voltage of HO2S SIG and SIG RTN circuit at suspect HO2S harness connector. Is the voltage less than 4.5 volts?	Yes	Replace HO2S and oil/filter. See HEATED OXYGEN SENSOR (HO2S) REMOVAL / INSTALLATION . Go to step 8.
5		No	Repair short to VPWR or VREF circuit. Go to step 8.
6	CHECK RESISTANCE OF HO2S SIGNAL CIRCUIT Disconnect PCM. Install breakout box, leave PCM disconnected. Measure resistance of the HO2S SIG circuit between PCM test pin 60 (DTC P0131) or PCM test pin 87 (DTC P0151) and the HO2S harness connector. Measure resistance of the SIG RTN circuit between PCM test pins 71/97 and the HO2S harness connector. Is each resistance less than 5.0 ohms?	Yes	Go to next step.
6		No	Repair open circuit. Go to step 8.
7	CHECK FOR SHORT TO VPWR Disconnect WDS or equivalent tester. For P0133 (front RH), measure the resistance between the following PCM test pins: 60 (HO2S SIG) and PCM test pins 71/97 For P0153 (front LH), measure the resistance between the following PCM test pins: 87 (HO2S SIG) and PCM test pins 71/97 Are the resistances greater than 10K ohms?	Yes	Replace PCM. See POWERTRAIN CONTROL MODULE (PCM) REMOVAL / INSTALLATION . Go to step 9.
7		No	Repair short circuit. Go to step 9.
8	DRIVE CYCLE Connect all disconnected connectors. Clear DTCs from PCM memory using WDS or equivalent tester. Perform fuel monitor or HO2S monitor drive cycle. See DRIVE CYCLES . Retrieve pending code. Is same DTC present?	Yes	Replace PCM. See POWERTRAIN CONTROL MODULE (PCM) REMOVAL / INSTALLATION . Go to next step.
8		No	Go to next step.
9	VERIFY TROUBLESHOOTING OF DTCs COMPLETED Perform PCM quick test. Is any DTC present?	Yes	Go to applicable DTC inspection. See DIAGNOSTIC TROUBLE CODE (DTC) INDEX - POWERTRAIN CONTROL MODULE (PCM) .
9		No	Troubleshooting is complete.