Code Definition
- DTC P1135: Air/Fuel Sensor Heater Circuit Malfunction (Bank 1, Sensor 1)
- DTC P1155: Air/Fuel Sensor Heater Circuit Malfunction (Bank 2, Sensor 1)
| CAUTION | If ECM replacement is instructed in following testing, always ensure ECM connectors and ground circuit are okay. If either are suspect, repair and repeat testing to confirm ECM malfunction. If ECM is replaced, ECM must be programmed with proper ignition key code for engine immobilizer system. For programming procedures, see COMPUTER RELEARN PROCEDURES - IMPORT article in GENERAL INFORMATION, or appropriate ENGINE IMMOBILIZER SYSTEMS article in ACCESSORIES & EQUIPMENT. |
Note. Bank 1 is also known as right bank (RH).
Note. For component location, see appropriate illustration in THEORY & OPERATION article.
Circuit Description
Air/Fuel (A/F) sensor monitors exhaust gas oxygen content and delivers an input signal to ECM. ECM uses input signal to control air/fuel ratio. A/F sensor includes a heater. DTC P1135 is for bank No. 1 A/F sensor. DTC P1155 is for bank No. 2 A/F sensor. DTC is set when A/F sensor heater output is more than 8 amps, or when heater output is less than .25 amp. Possible causes are
- A/F sensor heater circuit is open or shorted.
- Defective A/F sensor heater.
- Defective ECM.
Diagnostic Aids
Using scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.
Scheme 38
- Access ECM behind glove box. Turn ignition on. Using DVOM, backprobe at ECM harness connector and measure voltage between terminal No. 28 (Brown wire) at ECM connector E10 and terminals No. 4 (Black/White wire) and No. 3 (Black/Red wire) at ECM harness connector E9. see scheme 4 If both voltages are 9-14 volts, replace ECM. If either voltage is not 9-14 volts, go to next step.
- Disconnect suspect A/F sensor harness connector. Measure resistance between terminal No. 2 (Black wire on bank No. 1; Black/White wire on bank No. 2) and terminal No. 1 (Black/White wire on bank No. 1; Black/Red wire on bank No. 2) at A/F sensor connector (component side). see scheme 5 Resistance should be 1.8-3.4 ohms at 68°F (20°C) and 5.0-7.5 ohms at 932°F (500°C). If resistances are not as specified, replace appropriate A/F sensor. If resistances are as specified, go to next step.
- Check EFI ECU relay. see scheme 15 Replace relay as necessary. If relay is okay, check for open or short in wiring between relay and A/F sensor, and between A/F sensor and ECM. See «WIRING DIAGRAMS»(ref-134952) article. Repair as necessary.