I have an 07 F-150 FX4 5.4 Liter w/ 16000 miles. I am getting an error code: P0153 Heated Oxygen Sensor Circuit Slow Response (HO2S-21). Can some on explain this Code to me and if possible a repair for it. Thanks in advance!! Fordfrog.....

 

You're HEGO is probably bad. THe pcm expects to see the sensor switch very fast under normal operation. Your sensor is not switching fast, so either it's clogged or bad. However, since this is a emission related item, you're covered under warranty, so take it back to the dealer.

 

Thankyou for the reply what is a HEGO? Thanks again!!

 

Its your O2 sensor located on your cats. Your code is for bank 2 sensor 1.
But its covered under your warranty.

 

If it's a bank 2 sensor 1, that is not on your cat. It's post exhaust manifold. but PRE-cat. It will be on the driver side...

 

HEGO is Heated Exhaust Gas Oxgen Sensor. Sensor 1 is before the cats, post manifold and Sensor 2 is after the cats to monitor the effectiveness of the cats. Sensor 1s will switch very fast since that's your raw exhaust coming out of the engine so they constantly swtich from rich to lean, but should be right about Stoic (14.7 air/fuel mixture) during steady driving. Sensor 2s since they are after the cat, swtich slower since the cats are reducing the gases and are more stable. I can't remember which bank is which, you're covered under warranty.

 

Bank 2 are cyl# 5,6,7,8 which is drivers side. Sensor 1 is the top O2. (pre cat)

If your code was 22 than it would be bank 2 sensor 2. Which is the monitor O2 the bottom one.
If your code was 11 or 12
Bank 1 sensor 1 or bank 1 sensor 2