MPG Plummeted after service

agent_dess · January 27, 2023

Hey folks,

I had car serviced last Friday and ever since im getting 21-24mpg, prior to that for the same journeys it was 35-37mpg and longer journey would be 42mp avg.

I had a engine flush and fuel treatment this time.

And cannot blame the weather and its been alot milder lately. I double checked the air filter to make it was seated properly, so im at a loss to explain why the mpg ahs dropped so much.

I always run on E5.

Any suggestions?

wharfhouse · January 27, 2023

46 minutes ago, agent_dess said:

Hey folks,

I had car serviced last Friday and ever since im getting 21-24mpg, prior to that for the same journeys it was 35-37mpg and longer journey would be 42mp avg.

I had a engine flush and fuel treatment this time.

And cannot blame the weather and its been alot milder lately. I double checked the air filter to make it was seated properly, so im at a loss to explain why the mpg ahs dropped so much.

I always run on E5.

Any suggestions?

Perhaps something on the service that has changed / reset the ECU - if your style of driving had been economical then the car may have forgotten that - it should relearn after a while in that case. Or different fuel station - I have seen quite a difference in mpg between different fuel brands (E5 or E10).

NemesisUK · January 27, 2023

Could be as simple as a reset of the fuel history. If one reset this after refuelling the mpg plummets until the system records a few miles of driving.

agent_dess · January 27, 2023

Something seems a miss I often reset the mpg. Everything was fine before the service, at loss to explain why mpg is so poor in the past week.

PaulWhitt20 · January 27, 2023

Could the brakes be binding? Check if the wheels are hot after a drive.

Beamish · January 27, 2023

Check to ensure that the MAF sensor is connected.

agent_dess · January 27, 2023

27 minutes ago, Beamish said:

Check to ensure that the MAF sensor is connected.

Why would made sensor be disconnected? There would be no reason to disconnect it during a service. But I can double check.

agent_dess · January 27, 2023

1 hour ago, PaulWhitt20 said:

Could the brakes be binding? Check if the wheels are hot after a drive.

Possible but would have been picked up during service as they inspect the brakes but again it another thing I add to my list to check

agent_dess · January 27, 2023

I had to go for a slightly longer trip and it crept toward 27mpg. It's going back to Lexus Monday anyway which is 15miles so will see how much the mpg rises again.

wharfhouse · January 27, 2023

1 minute ago, agent_dess said:

I had to go for a slightly longer trip and it crept toward 27mpg. It's going back to Lexus Monday anyway which is 15miles so will see how much the mpg rises again.

How many miles have done since the service - if for some reason they had used up what was in the Hybrid Battery during the service and maybe drained down the 12v Battery (doors open etc) it would take quite a few miles to replenish those fully during which time the mpg would be low.

Bowserman · January 29, 2023

On 1/27/2023 at 6:42 PM, agent_dess said:

Possible but would have been picked up during service as they inspect the brakes but again it another thing I add to my list to check

Had mine in for 80k service and mot last week. Failed the mot on parking brake!

agent_dess · January 30, 2023

21 hours ago, Bowserman said:

Had mine in for 80k service and mot last week. Failed the mot on parking brake!

My Hybrid check failed P3000 code. They basically cleared it and said to drive 300 miles then they will retest it.
Today its away for ball-joint replacement, MOT in December said it was badly disentgrated, Lexus said the was a cut in it and advised immediate replacement... They are also going to do the wheel tracking/alignment as rear tyre were showing uneven inner ear. I got new tyres yesterday too.... money money money lol

agent_dess · January 30, 2023

On the plus side my drive to Lexus this morning meant my MPG was back at 46mpg 🙂

matt8 · January 30, 2023

Any more detail on the code? Seems P3000 is a bit broad or generic! I know it's for a Prius but still...

https://rennacs.com/p3000-prius-fault-code-diagnosis/

Hopefully can be sorted and not having to throw too much money at it.

agent_dess · January 30, 2023

1 hour ago, matt8 said:

Any more detail on the code? Seems P3000 is a bit broad or generic! I know it's for a Prius but still...

https://rennacs.com/p3000-prius-fault-code-diagnosis/

Hopefully can be sorted and not having to throw too much money at it.

Not yet, even today Lexus said i need to drive a min 300miles then bring the car back.

On the plus side the ball joint has been replaced, geometry corrected, even give me a discount on the repairs + they carried out the recall work and added 1/2 a tank of fuel.

ColinBarber · January 30, 2023

On 1/27/2023 at 11:15 AM, agent_dess said:

I had car serviced last Friday and ever since im getting 21-24mpg, prior to that for the same journeys it was 35-37mpg and longer journey would be 42mp avg.

Was the vehicle going in / out of EV mode by itself /shutting off the engine at junctions etc. There are conditions where this stops working although normally more common on older models such as the RX400h.

agent_dess · January 31, 2023

13 hours ago, ColinBarber said:

Was the vehicle going in / out of EV mode by itself /shutting off the engine at junctions etc. There are conditions where this stops working although normally more common on older models such as the RX400h.

Nope i've never noticed anything wrong with the car, but when they plugged in the device to run the hybrid check they said there was a historic DTC showing. They cleared and it said to drive 300 miles then come back and they will do the hybrid check for free. When i looked at the paperwork it stated P3000 code. Im wondering if might have gotten triggered when i removed and cleaned the hybrid fan (wouldn't have thought so). I've still got another 200 miles to do yet, so probably looking around mid Feb before i can go bacj.

wharfhouse · January 31, 2023

2 hours ago, agent_dess said:

Nope i've never noticed anything wrong with the car, but when they plugged in the device to run the hybrid check they said there was a historic DTC showing. They cleared and it said to drive 300 miles then come back and they will do the hybrid check for free. When i looked at the paperwork it stated P3000 code. Im wondering if might have gotten triggered when i removed and cleaned the hybrid fan (wouldn't have thought so). I've still got another 200 miles to do yet, so probably looking around mid Feb before i can go bacj.

They can have a problem running the test if the 12V Battery is low on charge for some reason. Not sure what error code that would report though. The advice is then to drive a few hundred miles and retest.