I just purchased a 2000 Mazda MPV, 51000 miles, California 2.5L engine. The engine light came on about 2 weeks weeks after I got it. The trouble code is P0051 - HO2S BANK 2 SENSOR 1 HEATER CIRCUIT LOW. Is this an oxygen sensor? Does it need replacing? Where is it located on my vehicle? Thanks! Denny
Thanks, Darkrooms! I drove the car this morning to drop kids off at school and the engine light was out. But my wife said it was still on when she drove yesterday. BTW: I like your occupation and interests! Do you know where this sensor is located on my engine? -Denny
Your Bank 2 refers to the bank of cylinders 2-4-6.(Bank 1 refers to 1-3-5) Bank 2 should be toward the front of the car. Now sensor 1 means the pre-catalyst sensor. Simply follow your exhaust pipe downwards until you reach the O2 sensor screwed into your exhaust pipe. It should only be a few inches away from the exhaust manifold. Yeah, I don't think alot of the younger people understand what sabaac is, but they better not be sith, cause I'll do em in!
Thank you very much for your detailed help. You are a true Jedi!
The code refers to you oxygen sensor's heater circuit. From the definition there's a problem with the circuit somewhere. Usually replacing the O2 sensor fixes it, but you'll want to check visually the connector for damage and you may evenwant to check for voltage at the connector with Key on Engine off.