C
Clark Kent
Guest
My brother has a 96 ford with a 300 cu. in. inline 6cyl. When he bought it(used) the dealer told him that both cats. were replaced. Shortly after driving it for a little while the check engine light came on. I scanned the codes and it came back with system lean bank 1, system lean bank 2, system heater malfunction, and dcc incomplete. To try and remedy this problem my brother had the injectors replaced, and with no suprise it didn't. I started to look at it and thought of the upstream O2 sensors. To test them I hooked up a voltmeter to the 1st bank O2 sensor and created a full lean situation by pulling the brake booster line. Then I created a full rich situation by introducing propane to the engine (via the booster line). The O2 sensor made little if no movment on the voltmeter. On the 2nd bank, with the same test, it made very little movement. Are the upstream O2 sensors bad?