Car Trouble Check Engine Light On
09-05-2012, 08:34 PM
#1
Thread Starter
Join Date: Aug 2012
Location: Texas
Posts: 7
Car Trouble Check Engine Light On
Well my car seems to be having some problems when i go into drive or reverse it feels like its gonna stall but then it accelerates itself and then goes back to normal i do have the check engine light on and its reading the code p1151 which I've looked up and says that the oxygen sensor detects to lean but i have no idea what could cause that and this is the only code its throwing at me nothing else so what do you guys think i should do? do i do a tune up or change fuel filter and try to clean the injectors what would you recommend thanks for the help ! ! 
09-05-2012, 09:24 PM
#2
TECH SAVANT
Join Date: Dec 2006
Location: Saint Augustine, FL
Posts: 10,938
Here is what the shop manual says about P1151, and the possible causes and diagnostic tips which are the same as P1130. Sensor H02S-21 is the front sensor on the driver's side.
This code means that the sensor is continuing to indicate a lean mixture when in fact the PCM has deliberately made the mix rich. This is the PCM's way of testing the sensors and indicates a strong probability of a bad sensor unless you have one of the other listed possible causes. It does NOT mean that the engine is running lean.
As it is only one bank that is reporting the issue it is unlikely that the cause would be something that would affect both banks--like fuel pressure, air leaks, EGR, etc. An exhaust leak before or near the sensor could cause the problem.
The sensor can be bench tested using a propane torch and a multimeter as described here; or if there is not exhaust leaks and the other possible causes do not seem to be at the root then just replace the sensor. They do not cost all that much but can be bitchy to changes on an older car--speaking of which how many miles on that '99?
This code means that the sensor is continuing to indicate a lean mixture when in fact the PCM has deliberately made the mix rich. This is the PCM's way of testing the sensors and indicates a strong probability of a bad sensor unless you have one of the other listed possible causes. It does NOT mean that the engine is running lean.
As it is only one bank that is reporting the issue it is unlikely that the cause would be something that would affect both banks--like fuel pressure, air leaks, EGR, etc. An exhaust leak before or near the sensor could cause the problem.
The sensor can be bench tested using a propane torch and a multimeter as described here; or if there is not exhaust leaks and the other possible causes do not seem to be at the root then just replace the sensor. They do not cost all that much but can be bitchy to changes on an older car--speaking of which how many miles on that '99?
09-05-2012, 09:55 PM
#4
TECH SAVANT
Join Date: Dec 2006
Location: Saint Augustine, FL
Posts: 10,938
Unless they have been changes at least once in that time them I'd replace them both--you will most likely see a boost in fuel economy as well as old and failing sensors output lower voltages and lower voltages tell the PCM the mix is lean when it isn't.
The PCM then richens the mix until the failing O² sensor tells it the AFR is 14.64:1, or until the fuel trim limit is reached and code(s) P1131 or P1151 are thrown...
The PCM then richens the mix until the failing O² sensor tells it the AFR is 14.64:1, or until the fuel trim limit is reached and code(s) P1131 or P1151 are thrown...
Thread
Thread Starter
Forum
Replies
Last Post
92 5.0stang
5.0L (1979-1995) Mustang
4
08-13-2015 06:46 AM