Toyota Repair: 1998 Camry PO171 with Engine hesitation at Road Speed.


Question
Ted,

I have a 1998 Camry with the 3.0 V6 that I use to commute to work. Recently the car started to hesitate 5 minutes after leaving home and the check engine light came on with a strong gas smell in the car.  I stopped at Advance Auto and used their scan tool to see what codes were set.

History:
P0125, B2796

Current:
Po171, P1130, P1133, P1150, P1153

I cleaned the MAF, replaced the PCV valve (stuck), checked the air intake to the throttle body for leaks and reset the error codes. Initially I thought the hesitation went away, but it came back after a short test drive and the check engine light came on.

Now the following codes are set.  

Confirmed:
PO125

Pending:
P0171, P1133 and P1153

I suspect the Bank 1 Sensor 1 Air/ fuel sensor because P0171 is bank 1 lean, but not sure because the other codes are for bank 1 and bank 2? Freeze frame data confirms PO125 with long term fuel trims for both banks at 52.3. I have limited tools to check vacuum, compression etc and may just break down and take it to my mechanic unless you have any suggestions.

Thanks,

Bill G

Answer
Hello, the P0125 code just means that the system is not going into a closed loop condition which means the computer doesn't see the correct voltages from the a/f and o2 sensors, this is understandable due to the lean condition (P0171) and as indicated by the fuel trim values.
1133 and 1153 are bank1 and bank2 a/f ratio sensor codes, I doubt that both are bad but it's possible, the lean code can affect both the sensors so the first thing is to take care of the lean condition then clear codes and see which come back, if any.
Double check to make sure no vacuum hoses or breather hoses are disconnected or leaking, no engine misfires are present, no rough erratic idling, check intake vacuum using a vacuum gauge directly at the intake chamber, should be around 18" hg on the gauge, anything much lower indicates an intake leak or mechanical problem. Check the timing belt, possibly worn and jumped on the gears.